CN114144309B - Inkjet printing device, method for aligning bipolar elements and method for manufacturing a display device - Google Patents

Inkjet printing device, method for aligning bipolar elements and method for manufacturing a display device Download PDF

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Publication number
CN114144309B
CN114144309B CN202080053265.1A CN202080053265A CN114144309B CN 114144309 B CN114144309 B CN 114144309B CN 202080053265 A CN202080053265 A CN 202080053265A CN 114144309 B CN114144309 B CN 114144309B
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China
Prior art keywords
electrode
electric field
ink
target substrate
light emitting
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CN202080053265.1A
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Chinese (zh)
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CN114144309A (en
Inventor
柳安娜
郭珍午
金性勳
李东浩
赵诚赞
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Samsung Display Co Ltd
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Samsung Display Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005Processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/14Structure thereof only for on-demand ink jet heads
    • B41J2/14016Structure of bubble jet print heads
    • B41J2/14072Electrical connections, e.g. details on electrodes, connecting the chip to the outside...
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/015Ink jet characterised by the jet generation process
    • B41J2/04Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/06Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/07Ink jet characterised by jet control
    • B41J2/075Ink jet characterised by jet control for many-valued deflection
    • B41J2/08Ink jet characterised by jet control for many-valued deflection charge-control type
    • B41J2/085Charge means, e.g. electrodes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/07Ink jet characterised by jet control
    • B41J2/075Ink jet characterised by jet control for many-valued deflection
    • B41J2/095Ink jet characterised by jet control for many-valued deflection electric field-control type
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/14Structure thereof only for on-demand ink jet heads
    • B41J2/1433Structure of nozzle plates
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/15Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
    • H01L27/156Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • H01L33/24Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate of the light emitting region, e.g. non-planar junction
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/44Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/14Structure thereof only for on-demand ink jet heads
    • B41J2002/14475Structure thereof only for on-demand ink jet heads characterised by nozzle shapes or number of orifices per chamber
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01Embodiments of or processes related to ink-jet heads
    • B41J2202/09Ink jet technology used for manufacturing optical filters

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Coating Apparatus (AREA)
  • Electroluminescent Light Sources (AREA)
  • Led Device Packages (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

An inkjet printing apparatus, a method for aligning bipolar elements, and a method for manufacturing a display device are provided. Inkjet printing devices are used to eject ink and include bipolar elements extending in one direction. The inkjet printing apparatus includes: an electric field generating unit including a stage and a probe unit for generating an electric field on the stage; and an inkjet head positioned above the stage and including a plurality of nozzles through which ink is ejected, wherein the nozzles include an inlet having a first diameter and an outlet connected to the inlet and having a second diameter smaller than the first diameter.

Description

Inkjet printing device, method for aligning bipolar elements and method for manufacturing a display device
Technical Field
The disclosure relates to an inkjet printing device, a method for aligning bipolar elements, and a method for manufacturing a display device.
Background
With the development of multimedia technology, the importance of display devices has steadily increased. In response to this, various types of display devices such as an organic light emitting display, a Liquid Crystal Display (LCD), and the like have been used.
The display device is a device for displaying an image, and includes a display panel such as an organic light emitting display panel or a liquid crystal display panel. The light emitting display panel may include a light emitting element (e.g., a Light Emitting Diode (LED)), and examples of the light emitting diode include an Organic Light Emitting Diode (OLED) using an organic material as a fluorescent material and an inorganic light emitting diode using an inorganic material as a fluorescent material.
An inorganic light emitting diode using an inorganic semiconductor as a fluorescent material has an advantage of durability even in a high temperature environment and has a higher blue light efficiency than an organic light emitting diode. In addition, in a manufacturing process, which is pointed out as a disadvantage of the conventional inorganic light emitting diode, a transfer method using a Dielectrophoresis (DEP) method has been developed. Accordingly, continuous research has been conducted on an inorganic light emitting diode having superior durability and efficiency as compared to an organic light emitting diode.
Meanwhile, the inkjet printing device may be used to transfer an inorganic light emitting diode element using a dielectrophoresis method or to form an organic material layer included in a display device. After ink-jet printing any ink or solution, a post-treatment process may be performed to transfer the inorganic light emitting diode element or to form an organic material layer. The inkjet printing apparatus may perform a process of supplying a predetermined ink or solution to an inkjet head and spraying the ink or solution onto a predetermined substrate using the inkjet head.
Disclosure of Invention
Technical problem
Aspects of the disclosure provide an inkjet printing device in which bipolar elements having a predetermined orientation may be ejected.
Aspects of the disclosure also provide a method for aligning a bipolar element with an improved alignment degree by using an inkjet printing apparatus, and a method for manufacturing a display apparatus including the bipolar element.
It should be noted that the various aspects of the disclosure are not so limited, and other aspects not mentioned herein will be apparent to one of ordinary skill in the art from the following description.
Technical proposal
According to a disclosed embodiment, an inkjet printing apparatus for ejecting ink including a bipolar element extending in one direction includes: an electric field generating unit including a stage and a probe unit generating an electric field on the stage; and an inkjet head positioned above the stage and including a plurality of nozzles from which ink is ejected, wherein the nozzles include an inlet having a first diameter and an outlet connected to the inlet and having a second diameter smaller than the first diameter.
In the nozzle, a first side surface, which is one side surface of the outlet, may extend in a first direction, and a second side surface, which is one side surface of the inlet, may be formed to be inclined with respect to the first direction.
Ink may be introduced into the outlet through the inlet and a bipolar element may be introduced into the outlet along the second side surface of the nozzle.
The bipolar element may be ejected from the outlet in a state in which its extending direction is parallel to the first direction.
The inkjet head may further include a guide member positioned between the plurality of nozzles, and the guide member may include a first guide member between the outlets and a second guide member between the inlets.
The inkjet head may further include an electric field generating electrode provided in the guide member.
The electric field generating electrode may include a first electric field generating electrode disposed on one surface of the first guide member in contact with the first side surface, and a second electric field generating electrode disposed on one surface of the second guide member in contact with the second side surface and spaced apart from the first electric field generating electrode in the first direction.
The first and second electric field generating electrodes may generate an electric field in the first direction at the inlet and the outlet.
The inkjet head may further include an electric field generating coil disposed to surround the nozzle.
The electric field generating coil may generate an electric field in a first direction at the inlet and the outlet.
The inkjet head may further include an inner tube connected to the inlet, and the first diameter of the inlet may decrease from the inner tube to the outlet.
The inkjet head may further include a plurality of third guide members disposed between the inlet and the inner tube, and the nozzle may further include an inlet tube formed by a separation space between the third guide members between the inner tube and the inlet.
Ink may be supplied from the inner tube to the inlet along the inlet tube, and the bipolar element may be introduced to the second side surface along one side surface of the inlet tube.
The ink jet head may be provided on a print head unit which is mounted on a carriage extending in one direction, and the print head unit may be movable in one direction.
The ejected ink may be sprayed onto the stage, and the electric field generating unit may generate an electric field on the stage.
The bipolar elements sprayed onto the mesa may be aligned by an electric field such that the direction of extension of the bipolar elements points in a second direction different from the first direction.
According to a disclosed embodiment, a method for aligning a bipolar element includes the steps of: spraying ink comprising a bipolar element oriented in one direction onto a target substrate; and generating an electric field over the target substrate to place the bipolar element on the target substrate.
The bipolar element may have a shape extending in one direction, and the step of spraying ink may be performed in a state in which an orientation direction of a long axis of the bipolar element is perpendicular to a top surface of the target substrate.
The step of spraying the ink may include generating an electric field in the ink such that the long axis of the bipolar element is oriented in a direction in which the electric field is directed.
The ink may be sprayed in a state in which the first end of the bipolar member is oriented toward the top surface of the target substrate.
The target substrate may include a first electrode and a second electrode, and the step of placing the bipolar element may include placing the bipolar element between the first electrode and the second electrode.
At least one end of the bipolar element may be disposed on at least one of the first electrode and the second electrode.
The step of spraying the ink onto the target substrate may be performed using an inkjet printing apparatus.
The inkjet printing apparatus may include: an electric field generating unit including a stage and a probe unit generating an electric field on the stage; and an inkjet head positioned above the stage and including a plurality of nozzles from which ink is ejected, and the nozzles may include an inlet having a first width and an outlet connected to the inlet and having a second width smaller than the first width.
According to a disclosed embodiment, a method for manufacturing a display device includes the steps of: preparing a target substrate having a first electrode and a second electrode formed thereon; spraying ink including a light emitting element oriented in one direction onto a target substrate; and placing the light emitting element between the first electrode and the second electrode.
The light emitting element may have a shape extending in one direction, and the step of spraying ink may be performed in a state in which an orientation direction of a long axis of the light emitting element is perpendicular to a top surface of the target substrate.
The step of placing the light emitting element may further include generating an electric field on the first electrode and the second electrode, and aligning an orientation direction of the light emitting element by the electric field.
Details of other embodiments are included in the detailed description and the accompanying drawings.
Advantageous effects
An inkjet printing device according to one embodiment may include nozzles having inclined side surfaces and different diameters in some regions, and bipolar elements dispersed in ink may be ejected in a state having an orientation direction perpendicular to a top surface of a target substrate and including an upward direction and/or a downward direction. In addition, in the inkjet printing apparatus, a member capable of generating an electric field may be further provided in the inkjet head, and the bipolar element may be ejected in an aligned state with a specific orientation direction.
Thus, the bipolar elements may be aligned with a high degree of alignment using an inkjet printing apparatus according to one embodiment.
Effects according to the embodiments are not limited to the above-exemplified matters, and further various effects are included in the present disclosure.
Drawings
Fig. 1 is a schematic perspective view of an inkjet printing apparatus according to one embodiment.
Fig. 2 is a schematic plan view of a printhead unit according to one embodiment.
Fig. 3 is a schematic diagram illustrating operation of a printhead unit according to one embodiment.
Fig. 4 is a schematic cross-sectional view of an inkjet head according to one embodiment.
Fig. 5 is a cross-sectional view showing ink ejected from an inkjet head according to one embodiment.
Fig. 6 is a schematic diagram showing ink ejected from an inkjet head according to one embodiment.
Fig. 7 is a schematic plan view of an electric field generating unit according to one embodiment.
Fig. 8 and 9 are schematic diagrams illustrating an operation of the probe unit according to an embodiment.
Fig. 10 is a schematic diagram illustrating generation of an electric field on a target substrate by an electric field generating unit according to one embodiment.
Fig. 11 is a schematic cross-sectional view of an inkjet head according to another embodiment.
Fig. 12 is an enlarged view of a portion Q1 of fig. 11.
Fig. 13 is a schematic cross-sectional view showing another example of the inkjet head of fig. 11.
Fig. 14 is a schematic cross-sectional view showing still another example of the inkjet head of fig. 11.
Fig. 15 is a schematic cross-sectional view of an inkjet head according to still another embodiment.
Fig. 16 is an enlarged view of a portion Q2 of fig. 15.
Fig. 17 is a schematic cross-sectional view of an inkjet head according to still another embodiment.
Fig. 18 is a schematic diagram showing ink flowing in the inkjet head of fig. 17.
Fig. 19 is a flow chart illustrating a method for aligning bipolar elements according to one embodiment.
Fig. 20 to 23 are cross-sectional views illustrating a method for aligning bipolar elements by using an inkjet printing apparatus according to one embodiment.
Fig. 24 is a schematic diagram of a light emitting element according to one embodiment.
Fig. 25 is a schematic view of a light emitting element according to another embodiment.
Fig. 26 is a schematic plan view of a display device according to an embodiment.
Fig. 27 is a plan view of one pixel of a display device according to one embodiment.
FIG. 28 is a cross-sectional view taken along lines Xa-Xa ', xb-Xb ' and Xc-Xc ' of FIG. 27.
Fig. 29 to 31 are cross-sectional views partially illustrating a method for manufacturing a display device according to one embodiment.
Detailed Description
The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It will also be understood that when a layer is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout the specification.
It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element discussed below could be termed a second element without departing from the teachings of the present invention. Similarly, a second element may also be referred to as a first element.
Hereinafter, embodiments will be described with reference to the drawings.
Fig. 1 is a schematic perspective view of an inkjet printing apparatus according to one embodiment.
Referring to fig. 1, an inkjet printing apparatus 1000 according to one embodiment includes a printhead unit 100 and an electric field generating unit 700, the printhead unit 100 including a plurality of inkjet heads 300 (see fig. 2). The inkjet printing apparatus 1000 may also include a base frame 600 and a station STA.
The inkjet printing apparatus 1000 may spray a predetermined ink 90 (see fig. 3) onto a target substrate SUB (see fig. 3) by using the print head unit 100. An electric field may be generated on the target substrate SUB on which the ink 90 is sprayed by the electric field generating unit 700, and particles, such as bipolar elements, included in the ink 90 may be aligned on the target substrate SUB.
The target substrate SUB may be disposed on the electric field generating unit 700, the electric field generating unit 700 may form an electric field over the target substrate SUB, and the electric field may be transferred to the ink 90 sprayed on the target substrate SUB. The particles such as bipolar elements included in the ink 90 may have a shape extending in one direction, and may be aligned by an electric field such that the extending direction points in one direction. Here, the inkjet printing apparatus 1000 according to one embodiment may include an inkjet head 300 to be described later, so that particles such as bipolar elements to be aligned on a target substrate SUB may be sprayed on the target substrate SUB in a state in which the long axis direction thereof is oriented perpendicular to the target substrate SUB and oriented to include an upward direction and a downward direction. In addition, the inkjet head 300 can prevent the nozzles 350 from which the ink 90 is ejected from being clogged with particles included in the ink 90. Hereinafter, the inkjet printing apparatus 1000 will be described in detail with reference to the drawings.
Meanwhile, in fig. 1, a first direction DR1, a second direction DR2, and a third direction DR3 are defined. The first direction DR1 and the second direction DR2 are located on one plane and are orthogonal to each other, and the third direction DR3 is a direction perpendicular to the first direction DR1 and the second direction DR 2. It is understood that the first direction DR1 refers to a horizontal direction in the drawing, the second direction DR2 refers to a vertical direction in the drawing, and the third direction DR3 refers to an up-down direction in the drawing.
Fig. 2 is a schematic plan view of a printhead unit according to one embodiment.
Referring to fig. 2 in combination with fig. 1, the inkjet printing apparatus 1000 includes a printhead unit 100 and an electric field generating unit 700, the printhead unit 100 including a plurality of inkjet heads 300. In addition, the inkjet printing apparatus 1000 may further include a stage STA on which the electric field generating unit 700 is disposed.
The station STA may provide an area in which the electric field generating unit 700 is disposed. The inkjet printing apparatus 1000 includes a first rail RL1 and a second rail RL2 extending in a second direction DR2, and a stage STA is provided on the first rail RL1 and the second rail RL 2. The table STA may move in the second direction DR2 by separate moving members on the first track RL1 and the second track RL 2. The electric field generating unit 700 may move in the second direction DR2 together with the stage STA, and the ink 90 may be sprayed over the electric field generating unit 700 while the electric field generating unit 700 passes through the printhead unit 100.
The print head unit 100 may include a plurality of inkjet heads 300 and may be disposed on the base frame 600. The print head unit 100 may spray a predetermined ink 90 onto a target substrate SUB disposed on the electric field generating unit 700 by using the ink jet head 300 connected to a separate ink storage unit.
Meanwhile, in one embodiment, the ink 90 may include a solvent 91 and a plurality of bipolar elements 95 (see fig. 5) included in the solvent 91. In an embodiment, the ink 90 may be provided in a solution or colloidal state. For example, the solvent 91 may be acetone, water, ethanol, toluene, propylene Glycol (PG), propylene Glycol Methyl Acetate (PGMA), or the like, but is not limited thereto. The plurality of bipolar elements 95 may be supplied to the print head unit 100 while being included in the solvent 91 in a dispersed state and ejected from the print head unit 100.
The base frame 600 may include a supporting unit 610 and a moving unit 630. The support unit 610 may include a first support member 611 extending in a first direction DR1 as a horizontal direction and a second support member 612 connected to the first support member 611 and extending in a third direction DR3 as an up-down direction. The extending direction of the first supporting member 611 may be the same as the first direction DR1, which is the longitudinal direction of the electric field generating unit 700. The print head unit 100 may be disposed on the moving unit 630 mounted on the first supporting member 611.
The moving unit 630 may include a moving member 631 mounted on the first supporting member 611 and movable in one direction, and a fixing member 632 provided on a bottom surface of the moving member 631 and on which the printing head unit 100 is placed. The moving member 631 may move in the first direction DR1 on the first supporting member 611, and the print head unit 100 may be fixed to the fixed member 632 to move in the first direction DR1 together with the moving member 631.
The print head unit 100 may be disposed on the base frame 600, and may spray the ink 90 supplied from the ink tank onto the target substrate SUB by the ink jet head 300 to be described later. The printhead unit 100 may be spaced apart from the stage STA passing under the base frame 600 by a predetermined distance. The distance between the print head unit 100 and the stage STA may be adjusted by the height of the second support part 612 of the base frame 600. The separation distance between the print head unit 100 and the stage STA may be adjusted within a range that can ensure a process space due to a certain distance between the print head unit 100 and the target substrate SUB when the electric field generating unit 700 and the target substrate SUB are disposed on the stage STA.
According to one embodiment, the printhead unit 100 may include an inkjet head 300 including a plurality of nozzles 350 (see fig. 5). The inkjet head 300 may be disposed on a bottom surface of the printhead unit 100.
The plurality of inkjet heads 300 may be disposed to be spaced apart from each other in one direction, and may be arranged in one or more rows. The figure shows that the inkjet heads 300 are arranged in two rows, and the inkjet heads 300 of each row are alternately arranged. However, the disclosure is not limited thereto, and the inkjet heads 300 may be arranged in a greater number of rows and may be disposed to overlap each other without intersecting each other. Although the shape of the inkjet head 300 is not particularly limited, the inkjet head 300 may have a quadrangular shape as an example.
At least one inkjet head 300 (e.g., two inkjet heads 300) may be disposed adjacent to each other to form a package. However, the number of the inkjet heads 300 included in one pack is not limited thereto, and for example, the number of the inkjet heads 300 included in one pack may be one to five. Further, although the drawing shows only six inkjet heads 300 provided in the print head unit 100, this schematically shows the print head unit 100, and the number of inkjet heads 300 is not limited thereto.
The inkjet head 300 provided in the printhead unit 100 may spray the ink 90 onto the target substrate SUB provided above the stage STA. According to one embodiment, the print head unit 100 may be moved in one direction on the first support member 611, and the inkjet head 300 may be moved in one direction to spray the ink 90 onto the target substrate SUB.
Fig. 3 is a schematic diagram illustrating operation of a printhead unit according to one embodiment. Fig. 3 illustrates a front view of the printhead unit 100 and the electric field generating unit 700 disposed on the stage STA according to one embodiment.
Referring to fig. 1 and 3, the print head unit 100 may move in a first direction DR1 along which the first supporting member 611 extends, and the inkjet head 300 may move in the first direction DR1 and spray the ink 90 onto the target substrate SUB. In some embodiments, the width of the target substrate SUB measured in the first direction DR1 may be greater than the width of the printhead unit 100. In this case, the print head unit 100 may move in the first direction DR1 and spray the ink 90 over the entire surface of the target substrate SUB. In addition, in the case where a plurality of target substrates SUB are disposed on the electric field generating unit 700, the print head unit 100 may spray the ink 90 onto each of the plurality of target substrates SUB while moving in the first direction DR 1.
However, the disclosure is not limited thereto, and the print head unit 100 may be positioned outside the first and second tracks RL1 and RL2 and then moved in the first direction DR1 to spray the ink 90 onto the target substrate SUB. When the stage STA moves in the second direction DR2 and is positioned below the base frame 600, the print head unit 100 may move between the first rail RL1 and the second rail RL2 to spray the ink 90 by the inkjet head 300. The operation of the inkjet head 300 is not limited thereto, and may be modified in various ways within the range in which it can be implemented. A detailed description of the operation of the inkjet head 300 will be omitted.
Fig. 4 is a schematic cross-sectional view of an inkjet head according to one embodiment. Fig. 5 is a cross-sectional view showing ink ejected from an inkjet head according to one embodiment.
Referring to fig. 4 and 5, the inkjet head 300 may include a plurality of nozzles 350 to eject the ink 90 through the nozzles 350. The ink 90 ejected from the nozzles 350 may be sprayed to the target substrate SUB disposed on the stage STA or the electric field generating unit 700. The nozzles 350 may be positioned on the bottom surface of the inkjet head 300, and may be arranged along one direction along which the inkjet head 300 extends.
The inkjet head 300 according to one embodiment may include a base member 310, an inner tube 330 to which ink 90 is supplied, a plurality of nozzles 350 connected to the inner tube 330 to eject the ink 90, and a guide member 370 positioned between the plurality of nozzles 350 of the base member 310.
The base member 310 may be a member constituting a main body of the inkjet head 300. The base member 310 may be attached to the printhead unit 100, and the inner tube 330 included in the base member 310 may be connected to an internal flow path of the printhead unit 100 so that the ink 90 may be supplied. The base member 310 may have a shape extending in one direction, and the inner tube 330 may be formed along the extending direction of the base member 310. The ink 90 supplied through the printhead unit 100 may be introduced along the inner tube 330 and may be ejected through the nozzles 350 of the inkjet head 300.
The inkjet head 300 may include a plurality of nozzles 350, and the base member 310 may include a guide member 370 between the plurality of nozzles 350. The plurality of nozzles 350 may be arranged to be spaced apart from each other, and a portion of the base member 310 between the nozzles 350 may be the guide member 370.
A plurality of nozzles 350 may be connected to the inner tube 330 and arranged along the extending direction of the base member 310. Although not shown in the drawings, the plurality of nozzles 350 may be arranged in one or more rows. In addition, although four nozzles 350 are illustrated as being formed in the inkjet head 300, the disclosure is not limited thereto. In some embodiments, the number of nozzles 350 included in the inkjet head 300 may be in the range of 128 to 1800.
The nozzle 350 may eject the ink 90 introduced along the inner tube 330. The amount of ink 90 sprayed through the nozzles 350 may be adjusted according to the voltage applied to each nozzle 350. In one embodiment, the amount of ink 90 ejected once from each nozzle 350 may be 1 picoliter (pL) to 50 picoliters (pL), but the disclosure is not limited thereto.
According to one embodiment, the nozzle 350 may include an inlet 351 having a first diameter R1 and an outlet 353 connected to the inlet 351 and having a second diameter R2 that is smaller than the first diameter R1. The inlet 351 is directly connected to the inner tube 330, and is a portion where the ink 90 flowing along the inner tube 330 is supplied to the nozzle 350. The outlet 353 is connected to the inlet 351, and the ink 90 supplied from the inlet 351 can be ejected through the outlet 353.
The bipolar elements 95 dispersed in the ink 90 may have a shape extending in one direction. The bipolar elements 95 randomly dispersed in the ink 90 may flow along the inner tube 330 and then be supplied to the nozzles 350. When the inlet of the inner tube 330 connected to the nozzle 350 has a narrow diameter, the bipolar elements 95 in the ink 90 may be supplied to the nozzle 350 in a clustered state, and a phenomenon in which the inlet of the nozzle 350 is blocked may occur. The inkjet head 300 according to one embodiment may include an inlet 351 having a first diameter R1 that is greater than a second diameter R2 of the outlet 353 to prevent the nozzle 350 from being blocked by the bipolar element 95. The first diameter R1 of the inlet 351 may be greater than the length of the long axis of the bipolar element 95, but is not limited thereto.
Since the bipolar elements 95 have a shape extending in one direction, the orientation direction (direction in which the long axes are directed) of the plurality of bipolar elements 95 can be determined. The plurality of bipolar elements 95 may be supplied to the inner tube 330 in the ink 90 in a state having a random orientation direction. However, when the ink 90 flowing through the inner tube 330 is supplied to the nozzle 350, the direction in which the long axis of the bipolar element 95 points (i.e., the orientation direction) may be changed according to the shape of the inlet 351.
The nozzles 350 of the inkjet head 300 may have inclined side surfaces in at least some regions. According to one embodiment, in the nozzle 350 of the inkjet head 300, the first side surface S1, which is one side surface of the outlet 353, may extend in one direction, and the second side surface S2, which is one side surface of the inlet 351, may be formed to be inclined with respect to the one direction. The first diameter R1 of the inlet 351 may decrease from the inner tube 330 toward the outlet 353. The inlet 351 has a larger diameter than the outlet 353, and a portion adjacent to the outlet 353 has a smaller diameter than a portion adjacent to the inner tube 330, so that the second side surface S2 may be formed to be inclined.
The ink 90 supplied from the inner tube 330 to the nozzle 350 may flow along the inclined side surface of the inlet 351. The bipolar elements 95 dispersed in the ink 90 flow along the second side surface S2 of the inlet 351, and when the bipolar elements 95 having random orientation directions flow along the second side surface S2, the orientation directions thereof may be changed. In the bipolar element 95 extending in one direction, the long axis direction thereof may be changed to an oblique direction parallel to the second side surface S2. Accordingly, the bipolar elements 95 dispersed in the ink 90 may have an orientation direction pointing in either direction.
Unlike the inlet 351, in the outlet 353 of the nozzle 350, the first side surface S1 may extend in one direction. The ink 90 introduced through the inlet 351 can be ejected while flowing along the first side surface S1 of the outlet 353 without changing the orientation direction. The bipolar element 95 introduced into the outlet 353 may have an orientation direction whose long axis direction is perpendicular to the target substrate SUB and includes an upward direction and a downward direction while flowing out from the inlet 351 along the second side surface S2 of the inlet 351, and may be ejected from the outlet 353 in a state having the orientation direction. According to one embodiment, the bipolar element 95 ejected from the inkjet head 300 may be ejected in a state in which the long axis direction is parallel to one direction along which the first side surface S1 of the outlet 353 extends.
As shown in fig. 5, the bipolar elements 95 supplied to the inner tube 330 flow in randomly oriented directions. However, the bipolar element 95 introduced into the outlet 353 through the inlet 351 of the nozzle 350 may be oriented such that one direction of extension is parallel to one direction along which the first side surface S1 extends. The ink 90 ejected from the nozzles 350 of the inkjet head 300 may include a plurality of bipolar elements 95 having arbitrary orientation directions in a dispersed state.
The base portion 310 of the inkjet head 300 may include a guide member 370 as a portion positioned between the nozzles 350, and the shapes of the side surfaces S1 and S2 and the diameters R1 and R2 of the inlet 351 and the outlet 353 may be determined according to the shape of the guide member 370. According to one embodiment, the inkjet head 300 may include a guide member 370 positioned between the plurality of nozzles 350, and the guide member 370 may include a first guide member 371 between the outlets 353 and a second guide member 372 between the inlets 351. As described above, the diameter R1 of the inlet 351 may be greater than the diameter R2 of the outlet 353, and similarly, the first width W1 of the first guide member 371 may be greater than the second width W2 of the second guide member 372. In addition, the second width W2 of the second guide member 372 may increase from the inner tube 330 toward the first guide member 371. Accordingly, the first diameter R1 of the inlet 351 between the second guide members 372 may be changed, and an inclined side surface may be formed.
The nozzle 350 having the first side surface S1 and the second side surface S2 can eject the ink 90 in a state where the plurality of bipolar elements 95 have an arbitrary orientation direction, and as described above, the ink 90 ejected from the inkjet head 300 can be sprayed onto the target substrate SUB.
Fig. 6 is a schematic diagram showing ink ejected from an inkjet head according to one embodiment.
Referring to fig. 6, ink 90 ejected from an inkjet head 300 is sprayed onto a target substrate SUB. Bipolar elements 95 having random orientations in inner tube 330 may be ejected through nozzle 350 in any orientation. In an embodiment, the ink 90 may be ejected from the inkjet head 300 in a state where the orientation direction of the long axis of the bipolar element 95 is perpendicular to the top surface of the target substrate SUB. In the ink 90 ejected from the inkjet head 300 and sprayed onto the target substrate SUB, the direction of the long axis of the bipolar element 95 may be directed toward the top surface of the target substrate SUB. As will be described later, the bipolar element 95 may be sprayed onto the target substrate SUB in an arbitrary orientation direction, and may be placed on the target substrate SUB in a specific orientation direction by an electric field generated by the electric field generating unit 700.
Meanwhile, the bipolar element 95 may include a first end having a first polarity and a second end having a second polarity. In the bipolar element 95 extending in one direction, a specific orientation direction may be defined based on the direction in which the first end faces. In fig. 5 and 6, the bipolar elements 95 dispersed in the ink 90 are shown facing in the upward and downward directions in the figures, rather than in a uniform direction in which the first ends face. That is, the expression described as having an arbitrary orientation direction in the exemplary embodiment may refer to an orientation direction having an upward direction and a downward direction including a top surface perpendicular to the target substrate SUB. However, the disclosure is not limited thereto. In some embodiments, the inkjet head 300 may further include means for generating an electric field in the nozzles 350 such that the first ends of the bipolar elements 95 dispersed in the ink 90 face in the same direction. The description may refer to other embodiments.
When the ink 90 including the bipolar element 95 is sprayed onto the target substrate SUB, the electric field generating unit 700 may generate an electric field over the target substrate SUB. By the electric field, the bipolar elements 95 included in the ink 90 can be aligned to have a specific orientation direction. Hereinafter, the electric field generating unit 700 will be described with reference to other figures.
Fig. 7 is a schematic plan view of an electric field generating unit according to one embodiment.
Referring to fig. 1 and 7, the electric field generating unit 700 may include a sub-stage 710, a probe holder 730, a probe unit 750, and an aligner 780.
The electric field generating unit 700 may be disposed on the station STA and may move in the second direction DR2 together with the station STA. The electric field generating unit 700 on which the target substrate SUB is disposed may move along the stage STA, and the ink 90 may be sprayed over the electric field generating unit 700. When spraying the ink 90, the electric field generating unit 700 may generate an electric field above the target substrate SUB.
The SUB-stage 710 may provide a space for setting the target substrate SUB. In addition, a probe holder 730, a probe unit 750, and an aligner 780 may be provided on the sub-stage 710. The shape of the sub-stage 710 is not particularly limited, but for example, as shown in the drawing, the sub-stage 710 may have a quadrangular shape with two sides extending in the first direction DR1 and the second direction DR 2. The sub-stage 710 may include a long side extending in the first direction DR1 and a short side extending in the second direction DR 2. However, the overall planar shape of the SUB-stage 710 may vary according to the shape of the target substrate SUB in a planar view. For example, when the target substrate SUB is rectangular in plan view, the shape of the SUB-stage 710 may be rectangular as shown in the drawing, and when the target substrate SUB has a circular planar shape, the SUB-stage 710 may also have a circular shape in plan view.
At least one aligner 780 may be provided on the submount 710. The aligner 780 may be provided on each side of the SUB-stage 710, and the region surrounded by the plurality of aligners 780 may be a region in which the target substrate SUB is provided. In the figure, two aligners 780 are shown disposed spaced apart on each side of the sub-stage 710, and a total of eight aligners 780 are disposed on the sub-stage 710. However, the disclosure is not limited thereto, and the number, arrangement, etc. of the aligners 780 may vary according to the shape or type of the target substrate SUB.
The probe holder 730 and the probe unit 750 are disposed on the sub-stage 710. The probe holder 730 may provide a space in which the probe unit 750 is disposed on the sub-stage 710. In particular, the probe holder 730 may be disposed on at least one side of the sub-stage 710 and extend along a direction along which the one side extends. For example, as shown in fig. 1, the probe holder 730 may be provided to extend in the second direction DR2 on the left and right sides of the sub-stage 710. However, the disclosure is not limited thereto, and a greater number of probe holders 730 may be included, and in some cases, the probe holders 730 may be disposed on upper and lower sides of the sub-stage 710 (see, for example, fig. 7). That is, the structure of the probe holder 730 may vary according to the number, configuration, structure, etc. of the probe units 750 included in the electric field generating unit 700.
The probe unit 750 may be disposed on the probe holder 730 to form an electric field on the target substrate SUB prepared on the submount 710. Similar to the probe holder 730, the probe unit 750 may extend in one direction (e.g., the second direction DR 2), and the extension length may cover the entire target substrate SUB. That is, the sizes and shapes of the probe holder 730 and the probe unit 750 may vary according to the target substrate SUB.
In one embodiment, the probe unit 750 may include a probe driver 753 disposed on the probe holder 730, a probe clip 751 disposed on the probe driver 753 to receive an electrical signal, and a probe pad (pad, or "bonding pad") 758 connected to the probe clip 751 to transmit an electrical signal to the target substrate SUB.
A probe driver 753 may be provided on the probe carriage 730 to move the probe clamp 751 and probe pad 758. In an embodiment, the probe driver 753 may move the probe jig 751 in a horizontal direction and an up-down direction (e.g., a first direction DR1 as a horizontal direction and a third direction DR3 as an up-down direction). The probe pad 758 may be connected to or separated from the target substrate SUB by driving of a probe driver 753. During the process of the inkjet printing apparatus 1000, in the step of forming an electric field over the target substrate SUB, the probe driver 753 may be driven to connect the probe pad 758 to the target substrate SUB, and in other steps, the probe driver 753 may be driven again to separate the probe pad 758 from the target substrate SUB. A detailed description thereof will be given later with reference to other figures.
Probe pad 758 can form an electric field on target substrate SUB by an electrical signal transmitted from probe clamp 751. Probe pad 758 may be connected to target substrate SUB and transmit electrical signals to form an electric field on target substrate SUB. For example, probe pad 758 may be in contact with an electrode or power pad of target substrate SUB, and an electrical signal of probe fixture 751 may be transmitted to the electrode or power pad. The electrical signal transmitted to the target substrate SUB may form an electric field on the target substrate SUB.
However, the disclosure is not limited thereto, and the probe pad 758 may be a member that forms an electric field by an electric signal transmitted from the probe jig 751. That is, when probe pad 758 receives an electrical signal to form an electric field, probe pad 758 may not be connected to target substrate SUB.
The shape of probe pad 758 is not particularly limited, but in an embodiment, probe pad 758 may have a shape extending in one direction to cover the entire target substrate SUB.
The probe clamp 751 can be connected to a probe pad 758 and can be connected to a separate voltage application device. The probe clamp 751 may transmit an electrical signal transmitted from the voltage applying device to the probe pad 758 to form an electric field on the target substrate SUB. The electrical signal transmitted to the probe clamp 751 can be a voltage (e.g., an Alternating Current (AC) voltage) used to form an electric field.
The probe unit 750 may include a plurality of probe jigs 751, and the number thereof is not particularly limited. Although the drawing shows three probe jigs 751 and three probe drivers 753 provided, the probe unit 750 may include a greater number of probe jigs 751 and probe drivers 753 to form an electric field having a higher density on the target substrate SUB.
The probe unit 750 according to one embodiment is not limited thereto. Although the drawing shows the probe unit 750 disposed on the probe holder 730 (i.e., the electric field generating unit 700), the probe unit 750 may be disposed as a separate device in some cases. The structure or configuration of the electric field generating unit 700 is not limited as long as it includes a device capable of forming an electric field and can form an electric field on the target substrate SUB.
Fig. 8 and 9 are schematic diagrams illustrating an operation of the probe unit according to an embodiment.
As described above, the probe driver 753 of the probe unit 750 may operate according to the process steps of the inkjet printing apparatus 1000. Referring to fig. 8 and 9, in a first state in which an electric field is not formed in the electric field generating unit 700, a probe unit 750 may be disposed on the probe carriage 730 to be spaced apart from the target substrate SUB. The probe driver 753 of the probe unit 750 may be driven in a first direction DR1, which is a horizontal direction, and a third direction DR3, which is an up-down direction, to separate the probe pad 758 from the target substrate SUB.
Next, in a second state where an electric field is formed on the target substrate SUB, the probe driver 753 of the probe unit 750 may be driven to connect the probe pad 758 to the target substrate SUB. The probe driver 753 may be driven in a third direction DR3 as an up-down direction and a first direction DR1 as a horizontal direction so that the probe pad 758 may be in contact with the target substrate SUB. The probe clamp 751 of the probe unit 750 may transmit an electrical signal to the probe pad 758 and may form an electric field on the target substrate SUB.
Meanwhile, it is shown in the drawing that one probe unit 750 is disposed on each of both sides of the electric field generating unit 700, and that two probe units 750 are simultaneously connected to the target substrate SUB. However, the disclosure is not limited thereto, and each of the plurality of probe units 750 may be individually driven. For example, when preparing the target substrate SUB on the SUB-stage 710 and spraying the ink 90 thereon, an arbitrary first probe unit 750 may first form an electric field on the target substrate SUB, and the second probe unit 750 may not be connected to the target substrate SUB. Thereafter, the first probe unit 750 may be separated from the target substrate SUB, and the second probe unit 750 may be connected to the target substrate SUB to form an electric field. That is, a plurality of probe cells 750 may be simultaneously driven to form an electric field, or each probe cell 750 may be sequentially driven to sequentially form an electric field.
Fig. 10 is a schematic diagram illustrating generation of an electric field on a target substrate by an electric field generating unit according to one embodiment.
Bipolar element 95 may be an object having a first polarity at one end and a second polarity different from the first polarity at the other end. For example, one end of the bipolar element 95 may have a positive polarity, and the other end of the bipolar element 95 may have a negative polarity. The bipolar elements 95 having different polarities at both ends may be subjected to electric power (attractive force and repulsive force) when placed in a predetermined electric field, and the orientation direction of the bipolar elements 95 may be controlled.
Referring to fig. 10, ink 90 including a bipolar element 95 is ejected from a nozzle 350 of an inkjet head 300. The ink 90 ejected from the nozzles 350 can be sprayed onto the target substrate SUB that will include the bipolar element 95 having an arbitrary orientation direction. When an electric field IEL is generated across the target substrate SUB, the bipolar element 95 having the first polarity and the second polarity may be subjected to electrical power until the ink 90 is placed on the target substrate SUB or even after placement. By means of electrical power, the bipolar element 95 may be oriented according to the polarity of the first and second ends. For example, the orientation direction of the bipolar element 95 may be the direction in which the electric field IEL is directed.
As described above, the bipolar element 95 ejected from the inkjet head 300 may be oriented such that its long axis direction is perpendicular to the top surface of the target substrate SUB. The electric field IEL generated on the target substrate SUB may be formed in a direction horizontal to the top surface of the target substrate SUB, and the orientation direction and position of the first and second ends of the bipolar element 95 may be changed along the direction of the electric field IEL. In an embodiment, the bipolar element 95 sprayed onto the target substrate SUB may be oriented by the electric field IEL such that the direction of extension points in a direction different from the direction perpendicular to the top surface of the target substrate SUB.
When an electric field IEL in a horizontal direction is generated on the target substrate SUB, the bipolar element 95 extending in one direction may be oriented such that the first and second ends face a direction parallel to the top surface of the target substrate SUB. Here, the bipolar element 95 may be oriented such that a first end having a first polarity faces one direction and a second end having a second polarity faces the other direction. The bipolar elements 95 ejected from the inkjet head 300 may be oriented such that the direction of their long axes is perpendicular to the top surface of the target substrate SUB, but the first end of each bipolar element 95 faces a random direction (including an upward direction and a downward direction perpendicular to the top surface of the target substrate SUB). Meanwhile, when the bipolar elements 95 are sprayed onto the target substrate SUB and the electric field IEL is generated, each of the bipolar elements 95 may be oriented such that the first ends thereof face the same direction and may be aligned on the target substrate SUB. The inkjet printing apparatus 1000 may align the bipolar element 95 on the target substrate SUB such that the first end has a particular orientation.
Since the bipolar element 95 ejected from the inkjet head 300 has an arbitrary orientation direction, the bipolar element 95 can be smoothly aligned according to the direction of the electric field IEL generated on the target substrate SUB. For the bipolar elements 95 oriented on the target substrate SUB, the orientation error of any one bipolar element 95 relative to the other bipolar elements 95 may be calculated, and the degree of alignment of the oriented bipolar elements 95 may be measured based thereon. The "alignment degree" of the bipolar element 95 may mean the degree of error between the orientation directions of the bipolar element 95 aligned on the target substrate SUB. For example, it is understood that when the error between the orientation directions of the bipolar elements 95 is large, the degree of alignment of the bipolar elements 95 is low, and when the error between the orientation directions of the bipolar elements 95 is small, the degree of alignment of the bipolar elements 95 is high or improved.
When the bipolar element 95 is sprayed onto the target substrate SUB in a state having random orientations, although the bipolar element 95 is subjected to electric power by the electric field IEL, the degree to which the bipolar element 95 is aligned to have a specific orientation direction may be insufficient. Meanwhile, the inkjet printing apparatus 1000 according to one embodiment can eject the bipolar element 95 in a state having an arbitrary orientation direction, so that the alignment degree of the bipolar element 95 aligned on the target substrate SUB can be improved.
Meanwhile, the point in time at which the electric field generating unit 700 generates the electric field IEL above the target substrate SUB is not particularly limited. The drawing shows that the probe unit 750 generates an electric field IEL while the ink 90 is ejected from the nozzle 350 and reaches the target substrate SUB. Accordingly, the bipolar element 95 may be subjected to a force due to the electric field IEL until the bipolar element 95 is ejected from the nozzle 350 and reaches the target substrate SUB. However, the disclosure is not limited thereto, and in some cases, the probe unit 750 may generate the electric field IEL after the ink 90 is sprayed onto the target substrate SUB. The electric field generating unit 700 may generate the electric field IEL when or after the ink 90 is sprayed from the inkjet head 300.
Although not shown in the drawings, in some embodiments, an electric field generating member may be further provided on the sub-stage 710. The electric field generating member may form an electric field in an upward direction (i.e., a third direction DR 3) or above the target substrate SUB, such as a probe unit 750, which will be described later. In an embodiment, an antenna unit or device including a plurality of electrodes may be used as the electric field generating member.
Meanwhile, although not shown in the drawings, the inkjet printing apparatus 1000 according to one embodiment may further include a heat treatment unit in which a process of evaporating the ink 90 sprayed onto the target substrate SUB is performed. The heat treatment unit may irradiate heat to the ink 90 sprayed on the target substrate SUB so that the solvent 91 of the ink 90 is evaporated and removed, and the bipolar element 95 may be disposed on the target substrate SUB. The process of removing the solvent 91 by radiating heat to the ink 90 may be performed by using a conventional heat treatment unit. A detailed description thereof will be omitted.
The inkjet printing apparatus 1000 may include a nozzle 350 in which the inkjet head 300 has a second side surface S2 that is inclined so that the bipolar element 95 may be ejected in a state having an arbitrary orientation direction. In the ink 90 sprayed onto the target substrate SUB, the bipolar elements 95 may have arbitrary orientation directions and may be dispersed, and the bipolar elements 95 may be aligned in a specific orientation direction by the electric field IEL generated by the electric field generating unit 700. The inkjet printing apparatus 1000 according to one embodiment may improve the alignment of the bipolar elements 95 aligned on the target substrate SUB.
Hereinafter, various embodiments of the inkjet printing apparatus 1000 will be described.
As described above, the bipolar element 95 may include a first end having a first polarity and a second end having a second polarity, and may have a particular orientation direction in which the first ends face. The inkjet head 300 according to one embodiment further includes a member that generates an electric field IEL in the nozzle 350 so that the bipolar element 95 to be ejected can be induced to have a specific orientation direction (the first ends of the bipolar elements 95 face the same direction).
Fig. 11 is a schematic cross-sectional view of an inkjet head according to another embodiment. Fig. 12 is an enlarged view of a portion Q1 of fig. 11.
Referring to fig. 11 and 12, the inkjet head 300_1 according to one embodiment may further include an electric field generating electrode 400_1 disposed on the guide member 370. The electric field generating electrode 400_1 may generate an electric field IEL in the nozzle 350 by an applied electric signal. The bipolar element 95 ejected through the nozzle 350 may be aligned such that the first and second ends having polarities face a specific direction by the electric field IEL generated by the electric field generating electrode 400_1. In an embodiment, the electric field generating electrode 400_1 provided on the guide member 370 may be further included so that the plurality of bipolar elements 95 dispersed in the ink 90 may be ejected in an aligned state such that the first ends face the same direction. The description of the other components is the same as that of the embodiment of fig. 4, and thus, hereinafter, redundant description will be omitted while focusing on differences.
The electric field generating electrode 400_1 may be disposed on a side surface of the guide member 370. The electric field generating electrode 400_1 may include a first electric field generating electrode 410_1 and a second electric field generating electrode 420_1, the first electric field generating electrode 410_1 may be disposed on one side surface of the first guide member 371, and the second electric field generating electrode 420_1 may be disposed on one side surface of the second guide member 372. The first electric field generating electrode 410_1 may be disposed on one side surface of the first guide member 371 to be disposed on the first side surface S1 of the outlet 353, and the second electric field generating electrode 420_1 may be disposed on one side surface of the second guide member 372 to be disposed on the second side surface S2 of the inlet 351. As described above, the first side surface S1 of the outlet 353 may have a shape extending in one direction, and the second side surface S2 of the inlet 351 may be formed to be inclined. Accordingly, the first electric field generating electrode 410_1 may be disposed on a side surface extending in one direction, and the second electric field generating electrode 420_1 may be disposed on a side surface formed to be inclined.
According to one embodiment, the first and second electric field generating electrodes 410_1 and 420_1 may be spaced apart from each other in one direction. The first and second electric field generating electrodes 410_1 and 420_1 may be disposed to be spaced apart from each other along a side surface of the nozzle 350. The first electric field generating electrode 410_1 may be disposed under the second electric field generating electrode 420_1.
The first and second electric field generating electrodes 410_1 and 420_1 may perform substantially the same function as the probe unit 750 of the electric field generating unit 700. However, the electric field generating electrode 400_1 is different from the electric field generating unit 700 in that the electric field generating electrode 400_1 is directly provided in the inkjet head 300.
A predetermined electric signal may be applied to the first and second electric field generating electrodes 410_1 and 420_1, and an electric field IEL may be generated between the first and second electric field generating electrodes 410_1 and 420_1. In an embodiment, the first and second electric field generating electrodes 410_1 and 420_1 may generate an electric field IEL in one direction along which the first side surface S1 extends at the inlet 351 and the outlet 353. The electric field IEL may align the bipolar elements 95 dispersed in the ink 90 such that the first ends having the first polarity face in the same direction. Unlike the embodiment of fig. 5, the inkjet head 300_1 of fig. 11 and 12 may further include an electric field generating electrode 400_1 so that the bipolar elements 95 to be ejected may be aligned and have a specific orientation direction so that the first ends have the same direction. Therefore, the bipolar elements 95 aligned so that the first ends thereof face the same direction can be dispersed in the ink 90 sprayed onto the target substrate SUB, and the bipolar elements 95 can be aligned smoothly by the electric field IEL generated by the electric field generating unit 700. That is, the inkjet printing apparatus 1000 further including the electric field generating electrode 400_1 can further improve the alignment degree of the bipolar element 95.
Fig. 13 is a schematic cross-sectional view showing another example of the inkjet head of fig. 11. Fig. 14 is a schematic cross-sectional view showing still another example of the inkjet head of fig. 11.
First, referring to fig. 13, the inkjet head 300_2 may include a greater number of electric field generating electrodes 400_2. The first electric field generating electrode 410_2 may be disposed on both side surfaces of the first guide member 371, and the second electric field generating electrode 420_2 may be disposed on both side surfaces of the second guide member 372. Accordingly, a stronger electric field IEL can be generated in the nozzle 350 of the inkjet head 300_2, and the bipolar element 95 can be ejected from the inkjet head 300_2 in an aligned state with a specific orientation direction. This embodiment is different from the embodiment of fig. 11 in that a greater number of electric field generating electrodes 400_2 are provided.
Next, referring to fig. 14, in the inkjet head 300_3, an electric field generating electrode 400_3 may be disposed to surround the nozzle 350. Accordingly, a uniform electric field IEL can be generated in the nozzle 350 of the inkjet head 300_3 according to the position, and the bipolar element 95 can be subjected to a force uniformly generated by the electric field IEL until the bipolar element 95 is ejected through the nozzle 350. This embodiment is different from the embodiment of fig. 13 in the configuration of the electric field generating electrode 400_3. Hereinafter, redundant description will be omitted.
Fig. 15 is a schematic cross-sectional view of an inkjet head according to still another embodiment. Fig. 16 is an enlarged view of a portion Q2 of fig. 15.
Referring to fig. 15 and 16, an inkjet head 300_4 according to one embodiment may include an electric field generating coil 500_4 disposed to surround a nozzle 350. The electric field generating coil 500_4 may generate an electric field IEL in one direction along which the coil extends by a flowing current. The electric field generating coil 500_4 disposed to surround at least the outlet 353 in the nozzle 350 may generate the electric field IEL along one direction along which the first side surface S1 of the outlet 353 extends. The bipolar element 95 introduced into the nozzle 350 may have a first end and a second end oriented according to the direction of the electric field IEL, and may be ejected from the inkjet head 300_4 in an aligned state having a specific orientation direction. This embodiment is different from the embodiment of fig. 11 in that the member generating the electric field IEL in the nozzle 350 of the inkjet head 300_4 is the electric field generating coil 500_4. Hereinafter, redundant description will be omitted.
Fig. 17 is a schematic cross-sectional view of an inkjet head according to still another embodiment. Fig. 18 is a schematic diagram showing ink flowing in the inkjet head of fig. 17.
Referring to fig. 17 and 18, the inkjet head 300_5 according to one embodiment may further include a plurality of third guide members 380_5 disposed between the inlet 351_5 and the inner tube 330_5, and the nozzle 350_5 may further include an inlet tube 355_5 formed by a separation space between the inner tube 330_5 and the third guide members 380_5 between the inlet 351_5. This embodiment is different from the embodiment of fig. 5 in that the ink-jet head 300_5 further includes a third guide member 380_5 such that the ink 90 flowing along the inner tube 330_5 is supplied to the inlet 351_5 through the inlet tube 355_5. In the following description, redundant description will be omitted while focusing on differences.
The third guide member 380_5 may be disposed on the second guide member 372_5. The third guide member 380_5 may have a shape extending in one direction, and may protrude from one side surface toward the other side surface of the inlet 351_5. The first guide member 371_5 and the second guide member 372_5 may be positioned between the plurality of nozzles 350_5, and the third guide member 380_5 may also be disposed between the plurality of nozzles 350_5. The inkjet head 300_5 may include a plurality of third guide members 380_5 that may be spaced apart from each other. The third guide member 380_5 may be disposed between the inner tube 330_5 and the inlet 351_5 of the nozzle 350_5, and the inlet tube 355_5 may be formed in a space spaced apart from the third guide member 380_5.
When the third guide member 380_5 is disposed between the inner tube 330_5 and the inlet 351_5, an inlet of the inlet 351_5 through which the ink 90 is supplied from the inner tube 330_5 may be narrowed. That is, the third diameter R3, which is the diameter of the inlet pipe 355_5, may be smaller than the first diameter R1, which is the diameter of the inlet 351_5. The ink 90 flowing along the inner tube 330_5 may be supplied to the inlet 351_5 through the inlet tube 355_5 having a narrow diameter. The flow rate of the ink 90 increases while flowing through the inlet pipe 355_5, and the ink 90 may be introduced into the outlet 353_5 at an increased flow rate along the inclined side surface of the inlet 351_5.
Fig. 18 schematically shows that the ink 90 is supplied to the inlet 351_5 through an inlet pipe 355_5 formed by the third guide member 380_5. Although not shown in fig. 18, it is understood that the third guide member 380_5 is positioned above and below the inlet pipe 355_5. As shown in the figure, the ink 90 flowing along the inner tube 330_5 may be supplied to the inlet 351_5 through the inlet tube 355_5. The ink 90 supplied from the inner tube 330_5 having a relatively wide diameter to the inlet tube 355_5 having a narrow diameter flows along the side surface of the inlet 351_5 at a high flow rate. In the embodiment, when the inlet 351_5 has a circular shape in a plan view, the ink 90 may flow while rotating along the side surface of the inlet 351_5, and may be introduced into the outlet 353_5 in a state having a rotational force.
As described above, the inlet 351_5 may be formed such that the second side surface S2, which is one side surface, is inclined, and the bipolar elements 95 dispersed in the ink 90 having a high flow rate may have an arbitrary orientation direction. The inkjet head 300_5 according to one embodiment may further include a third guide member 380_5 to guide the ejection of the bipolar element 95 having an arbitrary orientation direction from the nozzle 350_5. Thereafter, when the bipolar element 95 is sprayed onto the target substrate SUB, the bipolar element 95 may be aligned to have a specific orientation direction by the electric field IEL generated by the electric field generating unit 700. Hereinafter, redundant description will be omitted.
The above-described inkjet printing apparatus 1000 can eject the ink 90 having a state in which the bipolar elements 95 are arranged in an arbitrary direction. The ink 90 having a state in which the bipolar elements 95 are arranged is sprayed onto the target substrate SUB, and the electric field generating unit 700 generates an electric field IEL over the target substrate SUB on which the ink 90 is sprayed. The orientation direction and position of the bipolar element 95 may be changed by the electric field IEL, and the bipolar element 95 may be aligned in a specific direction on the target substrate SUB. Hereinafter, a method for aligning the bipolar element 95 using the inkjet printing apparatus 1000 according to one embodiment will be described in detail.
Fig. 19 is a flow chart illustrating a method for aligning bipolar elements according to one embodiment. Fig. 20 to 23 are cross-sectional views illustrating a method for aligning bipolar elements by using an inkjet printing apparatus according to one embodiment.
Referring to fig. 1 and 19-23, a method for aligning a bipolar element 95 according to one embodiment may include providing an inkjet printing apparatus 1000 (step S100), spraying ink 90 including the bipolar element 95 oriented in one direction onto a target substrate SUB (step S200), and placing the bipolar element 95 on the target substrate SUB (step S300).
The method for aligning the bipolar element 95 according to one embodiment may be performed using the inkjet printing apparatus 1000 described above with reference to fig. 1, and the bipolar element 95 may be ejected in a state of being oriented in either direction when the ink 90 is sprayed on the target substrate SUB. Thereafter, the bipolar element 95 may be aligned in one direction by the electric field IEL generated above the target substrate SUB.
First, the inkjet printing apparatus 1000 is set (step S100). Step S100 of setting up the inkjet printing apparatus 1000 is a step of debugging the inkjet printing apparatus 1000 according to a target process. For accurate debugging, an inkjet printing test process is performed on the inspection substrate, and the set value of the inkjet printing apparatus 1000 may be adjusted according to the result.
Specifically, the inspection substrate is first prepared. The inspection substrate may have the same structure as the target substrate SUB, but a bare substrate such as a glass substrate may be used.
Then, the top surface of the inspection substrate is treated with a waterproofing treatment. The waterproofing treatment may be performed by fluorine coating or plasma surface treatment.
Next, the ink 90 including the bipolar element 95 is sprayed onto the top surface of the inspection substrate using the inkjet printing apparatus 1000, and the droplet amount of each inkjet head 300 is measured. The measurement of the droplet amount for each inkjet head 300 may be performed by checking the size of the droplet when the droplet is sprayed and the size of the droplet applied to the substrate using a camera. When the measured droplet amount is different from the reference droplet amount, the voltage of each corresponding inkjet head 300 is adjusted so that the reference droplet amount can be ejected. This inspection method may be repeated several times until each inkjet head 300 ejects an accurate amount of liquid droplets.
However, the disclosure is not limited thereto, and the above-described step S100 of setting the inkjet printing apparatus may be omitted.
Next, when the setting of the inkjet printing apparatus 1000 is completed, as shown in fig. 20, a target substrate SUB is prepared. In an embodiment, the first electrode 21 and the second electrode 22 may be disposed on the target substrate SUB. Although the drawings show a pair of electrodes provided, a greater number of electrode pairs may be formed on the target substrate SUB, and the plurality of inkjet heads 300 may spray the ink 90 to each electrode pair in the same manner.
Subsequently, as shown in fig. 21, the ink 90 including the solvent 91 in which the bipolar member 95 is dispersed is sprayed on the target substrate SUB (step S200). The ink 90 may be ejected from the inkjet head 300 of the printhead unit 100, and may be sprayed onto the first electrode 21 and the second electrode 22 provided on the target substrate SUB. In particular, the inkjet head 300 according to one embodiment may include the nozzles 350, the nozzles 350 include the inlet 351 and the outlet 353 having different widths, and the bipolar elements 95 dispersed in the ink 90 may be ejected in a state oriented in one direction. The ink 90 may be sprayed onto the first electrode 21 and the second electrode 22 provided on the target substrate SUB, and one direction along which the bipolar element 95 dispersed in the ink 90 extends may be oriented in a direction perpendicular to the top surface of the target substrate SUB. In addition, although not shown in the drawings, when the inkjet head 300 is the inkjet head 300 of fig. 11 to 16, each of the bipolar elements 95 dispersed in the ink 90 may be sprayed in an aligned state in which the first end having the first polarity or the second end having the second polarity has the same direction. The description thereof is the same as the above description, and thus a detailed description thereof will be omitted.
Next, referring to fig. 22, an electric field IEL is generated on the target substrate SUB, and the bipolar element 95 is placed on the target substrate SUB by the electric field IEL (step S300). In some embodiments, the bipolar element 95 may be disposed between the first electrode 21 and the second electrode 22 by being subjected to dielectrophoretic forces by an electric field IEL generated above the target substrate SUB.
Specifically, an electrical signal is applied to the first electrode 21 and the second electrode 22 using the probe unit 750. The probe unit 750 may be connected to a predetermined pad (not shown) provided on the target substrate SUB, and may apply an electrical signal to the first electrode 21 and the second electrode 22 connected to the pad. In an embodiment, the electrical signal may be an AC voltage, and the AC voltage may have a voltage of ± (10 to 50) V and a frequency of 10kHz to 1 MHz. When an AC voltage is applied to the first electrode 21 and the second electrode 22, an electric field IEL is formed between the first electrode 21 and the second electrode 22, and the bipolar element 95 receives dielectrophoretic force caused by the electric field IEL. The dielectrophoresis force-receiving bipolar element 95 may be provided on the first electrode 21 and the second electrode 22 while its orientation direction and position are changed.
As shown in the figure, the orientation direction of the bipolar element 95 dispersed in the ink 90 and having one extending direction perpendicular to the target substrate SUB may be changed according to the direction of the electric field IEL. According to one embodiment, the bipolar elements 95 may be aligned by the electric field IEL such that one direction of extension points in the direction in which the electric field IEL points. When the electric field IEL generated on the target substrate SUB is generated parallel to the top surface of the target substrate SUB, the bipolar element 95 may be aligned such that the extending direction is parallel to the target substrate SUB, and may be disposed between the first electrode 21 and the second electrode 22. In some embodiments, the step of placing the bipolar element 95 is a step of placing the bipolar element 95 between the first electrode 21 and the second electrode 22, and at least one end of the bipolar element 95 may be disposed on at least one of the first electrode 21 and the second electrode 22. However, the disclosure is not limited thereto, and the bipolar element 95 may be directly disposed on the target substrate SUB between the first electrode 21 and the second electrode 22.
Next, as shown in fig. 23, the solvent 91 of the ink 90 sprayed onto the target substrate SUB is removed. The step of removing the solvent 91 is performed by a heat treatment device, and the heat treatment device may irradiate the target substrate SUB with heat or infrared rays. Since the solvent 91 is removed from the ink 90 sprayed onto the target substrate SUB, the flow of the bipolar element 95 can be prevented, and the bipolar element 95 can be placed on the first electrode 21 and the second electrode 22.
By the above-described method, the inkjet printing apparatus 1000 according to one embodiment can align the bipolar element 95 on the target substrate SUB.
Meanwhile, the above-described bipolar element 95 may be a light-emitting element including a plurality of semiconductor layers, and according to one embodiment, a display device including a light-emitting element may be manufactured using the inkjet printing device 1000.
Fig. 24 is a schematic diagram of a light emitting element according to one embodiment.
The light emitting element 30 may be a light emitting diode. Specifically, the light emitting element 30 may be an inorganic light emitting diode having a micro or nano size, and is made of an inorganic material. When an electric field is formed in a specific direction between two electrodes having polarities opposite to each other, the inorganic light emitting diode may be aligned between the two electrodes. The light emitting element 30 may be aligned between the two electrodes by an electric field generated between the electrodes.
The light emitting element 30 according to one embodiment may have a shape extending in one direction. The light emitting element 30 may have a shape of a rod, a wire, a tube, or the like. In an embodiment, the light emitting element 30 may have a cylindrical shape or a rod shape. However, the shape of the light emitting element 30 is not limited thereto, and the light emitting element 30 may have a polygonal prism shape such as a regular cube, a rectangular parallelepiped, or a hexagonal prism, or may have various shapes such as a shape extending in one direction and having a partially inclined outer surface. The plurality of semiconductors included in the light emitting element 30 to be described later may have a structure in which they are sequentially arranged or stacked along one direction.
The light emitting element 30 may include a semiconductor layer doped with any conductive type (e.g., p-type or n-type) impurity. The semiconductor layer may emit light of a specific wavelength band by receiving an electrical signal applied from an external power source.
Referring to fig. 24, the light emitting element 30 may include a first semiconductor layer 31, a second semiconductor layer 32, an active layer 33, an electrode layer 37, and an insulating film 38.
The first semiconductor layer 31 may be an n-type semiconductor. For example, when the light emitting element 30 emits light of blue wavelength band, the first semiconductor layer 31 may include a material having the chemical formula Al x Ga y In 1-x-y N (x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and x+y is more than or equal to 0 and less than or equal to 1). For example, it may be any one or more of n-doped AlGaInN, gaN, alGaN, inGaN, alN and InN. The first semiconductor layer 31 may be doped with an n-type dopant. For example, the n-type dopant may be Si, ge, se, sn, or the like. In an embodiment, the first semiconductor layer 31 may be n-GaN doped with n-type Si. The length of the first semiconductor layer 31 may have a range of 1.5 μm to 5 μm, but is not limited thereto.
The second semiconductor layer 32 is provided on an active layer 33 to be described later. The second semiconductor layer 32 may be a p-type semiconductor. For example, when the light emitting element 30 emits light in the blue or green wavelength band, the firstThe second semiconductor layer 32 may include a material having a chemical formula of Al x Ga y In 1-x-y N (x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and x+y is more than or equal to 0 and less than or equal to 1). For example, it may be any one or more of p-doped AlGaInN, gaN, alGaN, inGaN, alN and InN. The second semiconductor layer 32 may be doped with a p-type dopant. For example, the p-type dopant may be Mg, zn, ca, ba, or the like. In an embodiment, the second semiconductor layer 32 may be p-GaN doped with p-type Mg. The length of the second semiconductor layer 32 may have a range of 0.05 μm to 0.10 μm, but is not limited thereto.
Meanwhile, although the first semiconductor layer 31 and the second semiconductor layer 32 are illustrated as being configured as one layer in the drawings, the disclosure is not limited thereto. According to some embodiments, the first semiconductor layer 31 and the second semiconductor layer 32 may also include a greater number of layers, such as cladding layers or Tensile Strain Barrier Reduction (TSBR) layers, depending on the material of the active layer 33. A description thereof will be given later with reference to other figures.
The active layer 33 is disposed between the first semiconductor layer 31 and the second semiconductor layer 32. The active layer 33 may include a material having a single quantum well structure or a multiple quantum well structure. When the active layer 33 includes a material having a multi-quantum well structure, a plurality of quantum layers and well layers may be alternately stacked. The active layer 33 may emit light by combination of electron-hole pairs according to an electrical signal applied through the first semiconductor layer 31 and the second semiconductor layer 32. For example, when the active layer 33 emits light of a blue wavelength band, a material such as AlGaN or AlGaInN may be included. In particular, when the active layer 33 has a structure in which quantum layers and well layers are alternately stacked in a multiple quantum well structure, the quantum layers may include a material such as AlGaN or AlGaInN, and the well layers may include a material such as GaN or AlInN. In an embodiment, as described above, the active layer 33 includes AlGaInN as a quantum layer and AlGaInN as a well layer, and the active layer 33 may emit blue light having a center band of 450nm to 495 nm.
However, the disclosure is not limited thereto, and the active layer 33 may have a structure in which semiconductor materials having a large band gap and semiconductor materials having a small band gap are alternately stacked, and may include other group III to group V semiconductor materials according to the wavelength band of the emitted light. The light emitted by the active layer 33 is not limited to light of the blue wavelength band, but in some cases, the active layer 33 may also emit light of the red or green wavelength band. The length of the active layer 33 may have a range of 0.05 μm to 0.10 μm, but is not limited thereto.
Meanwhile, light emitted from the active layer 33 may be emitted to both side surfaces and an outer surface of the light emitting element 30 in the longitudinal direction. The directivity of light emitted from the active layer 33 is not limited to one direction.
The electrode layer 37 may be an ohmic contact electrode. However, the disclosure is not limited thereto, and may be a schottky contact electrode. The light emitting element 30 may include at least one electrode layer 37. Although fig. 24 shows that the light emitting element 30 includes one electrode layer 37, the disclosure is not limited thereto. In some cases, the light emitting element 30 may include a greater number of electrode layers 37, or may be omitted. The following description of the light emitting element 30 may be equally applied even if the number of the electrode layers 37 is different or other structures are also included.
In the display device 10 (for example, see fig. 26) according to one embodiment, when the light emitting element 30 is electrically connected to an electrode or a contact electrode, the electrode layer 37 may reduce the resistance between the light emitting element 30 and the electrode or the contact electrode. The electrode layer 37 may include a conductive metal. For example, the electrode layer 37 may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium Tin Oxide (ITO), indium Zinc Oxide (IZO), and Indium Tin Zinc Oxide (ITZO). In addition, the electrode layer 37 may include an n-type doped or p-type doped semiconductor material. The electrode layer 37 may include the same material or different materials, but is not limited thereto.
The insulating film 38 is arranged to surround the outer surfaces of the plurality of semiconductor layers and the electrode layer described above. In an embodiment, the insulating film 38 may be disposed to surround at least the outer surface of the active layer 33 and extend along the extending direction of the light emitting element 30. The insulating film 38 may function as a protective member. For example, the insulating film 38 may be formed to surround the side surfaces of the members to expose both ends of the light emitting element 30 in the longitudinal direction.
Although the insulating film 38 is shown in the drawing to extend in the longitudinal direction of the light emitting element 30 to cover the region from the first semiconductor layer 31 to the side surface of the electrode layer 37, the disclosure is not limited thereto. The insulating film 38 may cover only the outer surfaces of some of the semiconductor layers including the active layer 33, or may cover only a portion of the outer surfaces of the electrode layers 37 to partially expose the outer surface of each electrode layer 37. Further, in a cross-sectional view, the insulating film 38 may have a top surface that is circular in a region adjacent to at least one end of the light emitting element 30.
The thickness of the insulating film 38 may have a range of 10nm to 1.0 μm, but is not limited thereto. Preferably, the thickness of the insulating film 38 may be about 40 nm.
The insulating film 38 may include a material having insulating properties, for example, silicon oxide (SiO x ) Silicon nitride (SiN) x ) Silicon oxynitride (SiO) x N y ) Aluminum nitride (AlN) or aluminum oxide (Al) 2 O 3 ) Etc. Therefore, it is possible to prevent an electrical short circuit that may occur when the active layer 33 is in direct contact with an electrode through which an electrical signal is transmitted to the light emitting element 30. In addition, since the insulating film 38 protects the outer surface of the light emitting element 30 including the active layer 33, deterioration of light emitting efficiency can be prevented.
Further, in some embodiments, the insulating film 38 may have a surface treated outer surface. When manufacturing the display device 10, the light emitting elements 30 may be aligned by being sprayed on the electrodes in a state dispersed in a predetermined ink. Here, the surface of the insulating film 38 may be treated in a hydrophobic or hydrophilic manner so as to hold the light emitting elements 30 in a dispersed state without aggregation with other light emitting elements 30 adjacent in the ink.
The light emitting element 30 may have a length h of 1 μm to 10 μm or 2 μm to 6 μm, and preferably 3 μm to 5 μm. Further, the diameter of the light emitting element 30 may have a range of 30nm to 700nm, and the aspect ratio of the light emitting element 30 may be 1.2 to 100. However, the disclosure is not limited thereto, and the plurality of light emitting elements 30 included in the display device 10 may have different diameters according to the difference in composition of the active layer 33. Preferably, the diameter of the light emitting element 30 may be about 500nm.
The light emitting element 30 may have a shape extending in one direction. The light emitting element 30 may have a shape such as a nanorod, a nanowire, or a nanotube. In an embodiment, the light emitting element 30 may have a cylindrical or rod shape. However, the shape of the light emitting element 30 is not limited thereto, and may have various shapes such as a regular cube, a rectangular parallelepiped, and a hexagonal prism.
Meanwhile, the structure of the light emitting element 30 is not limited to that shown in fig. 24, and may have other structures.
Fig. 25 is a schematic view of a light emitting element according to another embodiment.
Referring to fig. 25, the light emitting element 30' may have a shape extending in one direction, and may have a side surface of a partially inclined shape. That is, the light emitting element 30' according to one embodiment may have a partial conical shape.
The light emitting element 30' may be formed such that a plurality of layers are not stacked in one direction, and each layer surrounds an outer surface of any other layer. The light emitting element 30' of fig. 25 may be formed such that a plurality of semiconductor layers surrounds at least a portion of the outer surface of any other layer. The light emitting element 30 'may include at least some regions of the semiconductor core extending in one direction and an insulating film 38' formed to surround the semiconductor core. The semiconductor core may include a first semiconductor layer 31', an active layer 33', a second semiconductor layer 32', and an electrode layer 37'. The light emitting element 30' of fig. 25 is identical to the light emitting element 30 of fig. 24 except that the shape portion of each of the layers is different. Hereinafter, the same contents will be omitted, and differences will be described.
According to one embodiment, the first semiconductor layer 31' may be formed to extend in one direction and have both ends inclined toward the center. The first semiconductor layer 31' of fig. 25 may include a body portion having a rod shape or a cylindrical shape, and end portions having inclined shapes formed on side surfaces thereof above and below the body portion, respectively. The upper end portion of the body portion may have a steeper inclination than the lower end portion.
The active layer 33 'is disposed around the outer surface of the body portion of the first semiconductor layer 31'. The active layer 33' may have a ring shape extending in one direction. The active layer 33 'may not be formed on the upper and lower end portions of the first semiconductor layer 31'. The active layer 33 'may be formed only on the non-inclined side surface of the first semiconductor layer 31'. However, it is not limited thereto. Accordingly, light emitted from the active layer 33' can be emitted not only from both ends of the light emitting element 30' in the longitudinal direction but also from both side surfaces of the light emitting element 30' with respect to the longitudinal direction. The light emitting element 30 'of fig. 25 has a larger area of the active layer 33' compared to the light emitting element 30 of fig. 24, so that a larger amount of light can be emitted.
The second semiconductor layer 32' is disposed to surround the outer surface of the active layer 33' and the upper end portion of the first semiconductor layer 31 '. The second semiconductor layer 32' may include a ring-shaped body portion extending in one direction and an upper end portion formed to be inclined at a side surface. That is, the second semiconductor layer 32' may be in direct contact with the parallel side surfaces of the active layer 33' and the inclined upper end portion of the first semiconductor layer 31 '. However, the second semiconductor layer 32 'is not formed on the lower end portion of the first semiconductor layer 31'.
The electrode layer 37 'is disposed around the outer surface of the second semiconductor layer 32'. That is, the shape of the electrode layer 37 'may be substantially the same as the shape of the second semiconductor layer 32'. That is, the electrode layer 37 'may be entirely in contact with the outer surface of the second semiconductor layer 32'.
The insulating film 38' may be disposed to surround the outer surfaces of the electrode layer 37' and the first semiconductor layer 31 '. The insulating film 38' may be in direct contact with the lower end portion of the first semiconductor layer 31' and the exposed lower end portions of the active layer 33' and the second semiconductor layer 32' (including the electrode layer 37 ').
According to one embodiment, the inkjet printing apparatus 1000 may disperse the light emitting elements 30 and 30' of fig. 24 or 25 in the ink 90 to be sprayed or jetted onto the target substrate SUB, thereby manufacturing the display apparatus 10 including the light emitting elements 30.
Fig. 26 is a schematic plan view of a display device according to an embodiment.
Referring to fig. 26, the display device 10 displays a moving image or a still image. Display device 10 may refer to any electronic device that provides a display screen. Examples of the display device 10 may include televisions, laptop computers, monitors, billboards, internet of things devices, mobile phones, smart phones, tablet Personal Computers (PCs), electronic watches, smartwatches, watch phones, head mounted displays, mobile communication terminals, electronic notebooks, electronic books, portable Multimedia Players (PMPs), navigation devices, gaming devices, digital cameras and video cameras, and the like, which provide a display screen.
The shape of the display device 10 may be variously modified. For example, the display device 10 may have a shape such as a rectangular shape elongated in a horizontal direction, a rectangular shape elongated in a vertical direction, a square shape, a quadrangular shape with rounded corners (vertices), other polygonal shapes, or a circular shape. The shape of the display area DA of the display device 10 may also be similar to the overall shape of the display device 10. In fig. 26, the display device 10 and the display area DA having a rectangular shape elongated in the horizontal direction are shown.
The display device 10 may include a display area DA and a non-display area NDA. The display area DA is an area where a screen can be displayed, and the non-display area NDA is an area where a screen is not displayed. The display area DA may also be referred to as an active area, and the non-display area NDA may also be referred to as a non-active area.
The display area DA may occupy substantially the center of the display device 10. The display area DA may include a plurality of pixels PX. The plurality of pixels PX may be arranged in a matrix. The shape of each pixel PX may be rectangular or square in plan view. However, the disclosure is not limited thereto, and it may be a diamond shape in which each side is inclined with respect to one direction. Each of the pixels PX may include one or more light emitting elements 30 emitting light of a specific wavelength band to display a specific color.
Fig. 27 is a schematic plan view of one pixel of a display device according to one embodiment.
Referring to fig. 27, each of the plurality of pixels PX may include a first subpixel PX1, a second subpixel PX2, and a third subpixel PX3. The first subpixel PX1 may emit light of a first color, the second subpixel PX2 may emit light of a second color, and the third subpixel PX3 may emit light of a third color. The first color may be blue, the second color may be green, the third color may be red, but is not limited thereto, and each subpixel PXn may emit light of the same color. In addition, although the pixel PX is illustrated in fig. 27 as including three sub-pixels PXn, the disclosure is not limited thereto, and the pixel PX may include a greater number of sub-pixels PXn.
Each subpixel PXn of the display device 10 may include an area defined as an emission area EMA. The first subpixel PX1 may include a first emission region EMA1, the second subpixel PX2 may include a second emission region EMA2, and the third subpixel PX3 may include a third emission region EMA3. The emission region EMA may be defined as a region at which the light emitting element 30 included in the display device 10 is disposed to emit light of a specific wavelength band.
Although not shown in the drawings, each subpixel PXn of the display device 10 may include a non-emission region defined as a region other than the emission region EMA. The non-emission region may be a region in which the light emitting element 30 is not disposed and a region from which light is not emitted because light emitted from the light emitting element 30 does not reach it.
Each subpixel PXn of the display device 10 includes a light emitting layer EML (see fig. 28). The light emitting layer EML may include at least one of a plurality of electrodes 21 and 22, a light emitting element 30, a plurality of contact electrodes 26, a plurality of inner banks 41 and 42 (see fig. 29), an outer bank 43, and insulating layers 51, 52, 53, and 55 (see fig. 28).
The plurality of electrodes 21 and 22 may be electrically connected to the light emitting element 30, and may be applied with a predetermined voltage such that the light emitting element 30 emits light of a specific wavelength band. In addition, at least a portion of each of the electrodes 21 and 22 may be used to form an electric field in the subpixel PXn to align the light emitting element 30.
The plurality of electrodes 21 and 22 may include a first electrode 21 and a second electrode 22. In an embodiment, the first electrode 21 may be a separate pixel electrode for each sub-pixel PXn, and the second electrode 22 may be a common electrode commonly connected along each sub-pixel PXn. One of the first electrode 21 and the second electrode 22 may be an anode electrode of the light emitting element 30, and the other may be a cathode electrode of the light emitting element 30. However, the disclosure is not limited thereto, and the reverse case may also be possible.
The first and second electrodes 21 and 22 may include respective electrode trunks 21S and 22S disposed to extend in the fourth direction DR4, and at least one respective electrode branches 21B and 22B extending from the electrode trunks 21S and 22S in a fifth direction DR5, the fifth direction DR5 being a direction intersecting the fourth direction DR 4.
The first electrode 21 may include a first electrode stem 21S disposed to extend in the fourth direction DR4, and at least one first electrode branch 21B branched from the first electrode stem 21S and extending in the fifth direction DR 5.
Both ends of the first electrode stem 21S of any one pixel may terminate due to a gap between the respective sub-pixels PXn, and the first electrode stem 21S may be placed on substantially the same straight line as the first electrode stem 21S of an adjacent (e.g., adjacent in the fourth direction DR 4) sub-pixel in the same row. Since the first electrode stems 21S provided in the respective sub-pixels PXn are arranged such that both ends thereof are spaced apart from each other, it may be possible to apply different electrical signals to the first electrode branches 21B, so that the first electrode branches 21B may be driven individually.
The first electrode branch 21B may branch from at least a portion of the first electrode trunk 21S, and be disposed to extend in the fifth direction DR5, and may terminate while being spaced apart from the second electrode trunk 22S disposed to face the first electrode trunk 21S.
The second electrode 22 may include a second electrode stem 22S extending in the fourth direction DR4 and spaced apart from the first electrode stem 21S in the fifth direction DR5 to face the first electrode stem 21S, and a second electrode branch 22B branched from the second electrode stem 22S and extending in the fifth direction DR 5. The other end of the second electrode trunk 22S may be connected to the second electrode trunk 22S of another sub-pixel PXn adjacent in the fourth direction DR 4. That is, unlike the first electrode trunk 21S, the second electrode trunk 22S may extend in the fourth direction DR4 and may be disposed to pass through each sub-pixel PXn. The second electrode trunk 22S passing through each sub-pixel PXn may be connected to a portion extending in one direction in the non-display area NDA or in an external portion of the display area DA where the corresponding pixel PX or sub-pixel PXn is placed.
The second electrode branch 22B may be spaced apart from the first electrode branch 21B and face the first electrode branch 21B, and may terminate while being spaced apart from the first electrode trunk 21S. The second electrode branch 22B may be connected to the second electrode trunk 22S, and one end in the extending direction may be disposed in the sub-pixel PXn while being spaced apart from the first electrode trunk 21S.
The first electrode 21 and the second electrode 22 may be electrically connected to a circuit element layer (not shown) of the display device 10 through contact holes (e.g., first electrode contact hole CNTD and second electrode contact hole CNTS), respectively. The drawing shows that the first electrode contact hole CNTD is formed for each of the first electrode stems 21S of each subpixel PXn, and only one second electrode contact hole CNTS is formed on one second electrode stem 22S passing through each subpixel PXn. However, the disclosure is not limited thereto, and in some cases, the second electrode contact hole CNTS may be formed even for each subpixel PXn.
The plurality of banks 41, 42, and 43 may include an outer bank 43 disposed at a boundary between the respective sub-pixels PXn, and a plurality of inner banks 41 and 42 adjacent to a center of each sub-pixel PXn and disposed under each of the electrodes 21 and 22. Although a plurality of inner banks 41 and 42 are not shown in the drawings, the first inner bank 41 and the second inner bank 42 may be disposed under the first electrode branch 21B and the second electrode branch 22B, respectively.
The outer bank 43 may be disposed at a boundary between the respective sub-pixels PXn. The plurality of first electrode stems 21S may terminate such that their respective ends are spaced apart from each other with the outer dike 43 interposed therebetween. The outer bank 43 may extend in the fifth direction DR5 and may be disposed at a boundary between the sub-pixels PXn arranged in the fourth direction DR 4. However, the disclosure is not limited thereto, and the outer bank 43 may extend in the fourth direction DR4, and may also be disposed at a boundary between the sub-pixels PXn arranged in the fifth direction DR 5. By including the same material as the inner banks 41 and 42, the outer banks 43 can be formed simultaneously in one process.
The light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22. The light emitting element 30 may have one end electrically connected to the first electrode 21 and the other end electrically connected to the second electrode 22. The light emitting element 30 may be electrically connected to each of the first electrode 21 and the second electrode 22 through a contact electrode 26 described later.
The plurality of light emitting elements 30 may be disposed spaced apart from each other and aligned substantially parallel to each other. The distance between the light emitting elements 30 is not particularly limited. In some cases, a plurality of light emitting elements 30 may be disposed adjacent to each other to form a group, and a plurality of other light emitting elements 30 may be grouped while being spaced apart from each other by a predetermined interval, and may have a non-uniform density but be aligned by being oriented in one direction. Further, in the embodiment, the light emitting element 30 may have a shape extending in one direction, and the extending direction of the electrodes (e.g., the first electrode branch 21B and the second electrode branch 22B) may be substantially perpendicular to the extending direction of the light emitting element 30. However, the disclosure is not limited thereto, and the light emitting element 30 may be disposed diagonally with respect to the extending direction of the first electrode branch 21B and the second electrode branch 22B, not perpendicular to the extending direction of the first electrode branch 21B and the second electrode branch 22B.
The light emitting element 30 according to one embodiment may have the active layer 33 including different materials, and thus may emit light of different wavelength bands to the outside. In the display device 10, the light emitting element 30 of the first subpixel PX1 may emit first light having a center wavelength band of a first wavelength, the light emitting element 30 of the second subpixel PX2 may emit second light having a center wavelength band of a second wavelength, and the light emitting element 30 of the third subpixel PX3 may emit third light having a center wavelength band of a third wavelength. Accordingly, the first light may be emitted from the first subpixel PX1, the second light may be emitted from the second subpixel PX2, and the third light may be emitted from the third subpixel PX 3. In some embodiments, the first light may be blue light having a center band in the range of 450nm to 495nm, the second light may be green light having a center band in the range of 495nm to 570nm, and the third light may be red light having a center band in the range of 620nm to 750 nm. However, the disclosure is not limited thereto.
Although not shown in fig. 27, the display device 10 may include a second insulating layer 52 covering at least a portion of the first electrode 21 and the second electrode 22.
The second insulating layer 52 may be disposed in each subpixel PXn of the display device 10. The second insulating layer 52 may be disposed to cover each sub-pixel PXn substantially entirely, and may also be disposed to extend to other adjacent sub-pixels PXn. The second insulating layer 52 may be provided to cover at least a portion of the first electrode 21 and the second electrode 22. Although not shown in fig. 27, the second insulating layer 52 may be provided to expose a portion of the first electrode 21 and the second electrode 22 (specifically, some regions of the first electrode branch 21B and the second electrode branch 22B).
The plurality of contact electrodes 26 may have a shape in which at least some regions extend in one direction. The plurality of contact electrodes 26 may be in contact with the light emitting element 30 and the electrodes 21 and 22, respectively, and the light emitting element 30 may receive an electrical signal from the first electrode 21 and the second electrode 22 through the contact electrodes 26.
The contact electrode 26 may include a first contact electrode 26a and a second contact electrode 26b. The first contact electrode 26a and the second contact electrode 26B may be disposed on the first electrode branch 21B and the second electrode branch 22B, respectively.
The first contact electrode 26a may be disposed on the first electrode 21 or the first electrode branch 21B to extend in the fifth direction DR 5. The first contact electrode 26a may be in contact with one end of the light emitting element 30. In addition, the first contact electrode 26a may be in contact with the exposed first electrode 21 without being disposed on the second insulating layer 52. Accordingly, the light emitting element 30 may be electrically connected to the first electrode 21 through the first contact electrode 26 a.
The second contact electrode 26B may be disposed on the second electrode 22 or the second electrode branch 22B to extend in the fifth direction DR 5. The second contact electrode 26b may be spaced apart from the first contact electrode 26a in the fourth direction DR 4. The second contact electrode 26b may be in contact with the other end of the light emitting element 30. In addition, the second contact electrode 26b may be in contact with the exposed second electrode 22 without being disposed on the second insulating layer 52. Accordingly, the light emitting element 30 may be electrically connected to the second electrode 22 through the second contact electrode 26b. Although two first contact electrodes 26a and one second contact electrode 26b are shown disposed in one sub-pixel PXn, the disclosure is not limited thereto. The number of the first and second contact electrodes 26a and 26B may be changed according to the number of the first and second electrodes 21 and 22 (or the first and second electrode branches 21B and 22B) provided in each subpixel PXn.
In some embodiments, the widths of the first and second contact electrodes 26a and 26B measured in one direction may be greater than the widths of the first and second electrodes 21 and 22 (or the first and second electrode branches 21B and 22B), respectively, measured in one direction. However, the disclosure is not limited thereto, and in some cases, the first contact electrode 26a and the second contact electrode 26B may be disposed to cover only one side portion of the first electrode branch 21B and the second electrode branch 22B.
Meanwhile, the display device 10 may include, in addition to the second insulating layer 52, a circuit element layer (not shown) positioned under each of the electrodes 21 and 22, a third insulating layer 53 (see fig. 28) disposed to cover at least a portion of each of the electrodes 21 and 22 and the light emitting element 30, and a passivation layer 55 (see fig. 28). Hereinafter, the structure of the display device 10 will be described in detail with reference to fig. 28.
FIG. 28 is a cross-sectional view taken along lines Xa-Xa ', xb-Xb ' and Xc-Xc ' of FIG. 27.
Fig. 28 shows only the cross section of the first subpixel PX1, but it may be applied to other pixels PX or subpixels PXn. Fig. 28 shows a cross section through one end and the other end of the light emitting element 30 provided in the first subpixel PX 1.
Meanwhile, although not shown in fig. 28, the display device 10 may further include a circuit element layer positioned under each of the electrodes 21 and 22. The circuit element layer may include a plurality of semiconductor layers and a plurality of conductive patterns, and may include at least one transistor and a power line. However, a detailed description thereof will be omitted below.
Referring to fig. 28 in combination with fig. 27, the display device 10 may include a first insulating layer 51, electrodes 21 and 22 disposed on the first insulating layer 51, a light emitting element 30, and the like. A circuit element layer (not shown) may be further disposed under the first insulating layer 51. The first insulating layer 51 may include an organic insulating material to perform a surface planarization function.
The plurality of banks 41, 42, and 43, the plurality of electrodes 21 and 22, and the light emitting element 30 may be disposed on the first insulating layer 51.
The plurality of banks 41, 42, and 43 may include inner banks 41 and 42 disposed spaced apart from each other in each sub-pixel PXn, and outer banks 43 disposed at boundaries of adjacent sub-pixels PXn.
The outer bank 43 may extend in the fifth direction DR5 and may be disposed at a boundary between the sub-pixels PXn arranged in the fourth direction DR 4. However, the disclosure is not limited thereto, and the outer bank 43 may extend in the fourth direction DR4, and may also be disposed at a boundary between the sub-pixels PXn arranged in the fifth direction DR 5. That is, the outer bank 43 may define a boundary of each sub-pixel PXn.
When the ink in which the light emitting elements 30 are dispersed is sprayed using the inkjet printing apparatus 1000 of fig. 1 described above at the time of manufacturing the display apparatus 10, the outer bank 43 may perform a function of preventing the ink from passing through the boundary of the sub-pixel PXn. In order not to mix the inks in which the different light emitting elements 30 are dispersed for each of the different sub-pixels PXn with each other, the external dykes 43 can separate the inks. However, it is not limited thereto.
The plurality of inner banks 41 and 42 may include a first inner bank 41 and a second inner bank 42 disposed adjacent to the center of each sub-pixel PXn.
The first and second inner banks 41 and 42 are spaced apart from each other and disposed to face each other. The first electrode 21 may be disposed on the first inner bank 41, and the second electrode 22 may be disposed on the second inner bank 42. Referring to fig. 27 and 28, it can be understood that the first electrode branch 21B is disposed on the first inner bank 41, and the second electrode branch 22B is disposed on the second inner bank 42.
The first and second inner banks 41 and 42 may be disposed to extend in the fifth direction DR5 in each sub-pixel PXn. However, the disclosure is not limited thereto, and the first and second inner banks 41 and 42 may be provided for each sub-pixel PXn to form a pattern on the front surface of the display device 10. The plurality of banks 41, 42 and 43 may include Polyimide (PI), but are not limited thereto.
The first and second inner banks 41 and 42 may have a structure in which at least a portion thereof protrudes with respect to the first insulating layer 51. The first and second inner banks 41 and 42 may protrude upward beyond a plane on which the light emitting element 30 is disposed, and at least a portion of the protruding portion may have an inclination. Since the inner banks 41 and 42 protrude with respect to the first insulating layer 51 and have inclined side surfaces, light emitted from the light emitting element 30 may be reflected from the inclined side surfaces of the inner banks 41 and 42. As will be described later, when the electrodes 21 and 22 provided on the inner banks 41 and 42 include a material having a high reflectance, light emitted from the light emitting element 30 may be reflected by the electrodes 21 and 22 and may travel in an upward direction of the first insulating layer 51.
As described above, by including the same material, the plurality of banks 41, 42, and 43 can be formed in the same process. However, the outer bank 43 is disposed at the boundary of each sub-pixel PXn to form a grid pattern, but the inner banks 41 and 42 are disposed within each sub-pixel PXn to have a shape extending in one direction.
A plurality of electrodes 21 and 22 may be disposed on the first insulating layer 51 and the inner banks 41 and 42. As described above, each of the electrodes 21 and 22 includes the electrode stems 21S and 22S and the electrode branches 21B and 22B.
Some regions of the first and second electrodes 21 and 22 may be disposed on the first insulating layer 51, and some regions of the first and second electrodes 21 and 22 may be disposed on the first and second inner banks 41 and 42. As described above, the first electrode stem 21S of the first electrode 21 and the second electrode stem 22S of the second electrode 22 may extend in the fourth direction DR4, and the first and second inner banks 41 and 42 may extend in the fifth direction DR5, and may also be disposed in the sub-pixels PXn adjacent in the fifth direction DR 5.
A first electrode contact hole CNTD penetrating the first insulating layer 51 and exposing a portion of the circuit element layer may be formed in the first electrode stem 21S of the first electrode 21. The first electrode 21 may be electrically connected to the transistor of the circuit element layer through the first electrode contact hole CNTD. The first electrode 21 may receive a predetermined electric signal from the transistor.
The second electrode stem 22S of the second electrode 22 may extend in one direction so as to be also disposed in a non-emission region where the light emitting element 30 is not disposed. A second electrode contact hole CNTS penetrating the first insulating layer 51 and exposing a portion of the circuit element layer may be formed in the second electrode stem 22S. The second electrode 22 may be electrically connected to the power supply electrode through the second electrode contact hole CNTS. The second electrode 22 may receive a predetermined electrical signal from the power electrode.
Regions of the first and second electrodes 21 and 22 (e.g., the first and second electrode branches 21B and 22B) may be disposed on the first and second inner banks 41 and 42, respectively. The plurality of light emitting elements 30 may be disposed in a region between the first electrode 21 and the second electrode 22, that is, in a space where the first electrode branch 21B and the second electrode branch 22B are spaced apart and face each other.
Each of the electrodes 21 and 22 may include a transparent conductive material. For example, each of the electrodes 21 and 22 may include a material such as Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), or Indium Tin Zinc Oxide (ITZO), but is not limited thereto. In some embodiments, each of the electrodes 21 and 22 may include a conductive material having a high reflectivity. For example, each of the electrodes 21 and 22 may include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a material having high reflectivity. In this case, light incident on each of the electrodes 21 and 22 may be reflected and emitted in an upward direction of each of the sub-pixels PXn.
Further, each of the electrodes 21 and 22 may have a structure in which at least one transparent conductive material and at least one metal layer having high reflectivity are stacked, or may be formed to include one layer thereof. In an embodiment, each of the electrodes 21 and 22 may have a stack structure of ITO/silver (Ag)/ITO/IZO, or may be an alloy including aluminum (Al), nickel (Ni), lanthanum (La), or the like. However, it is not limited thereto.
The second insulating layer 52 is disposed on the first insulating layer 51, the first electrode 21, and the second electrode 22. The second insulating layer 52 is provided to partially cover the first electrode 21 and the second electrode 22. The second insulating layer 52 may be disposed to largely cover the top surfaces of the first and second electrodes 21 and 22 and partially expose the first and second electrodes 21 and 22. The second insulating layer 52 may be disposed to expose a portion of the top surfaces of the first and second electrodes 21 and 22, for example, a portion of the top surface of the first electrode branch 21B disposed on the first inner bank 41 and a portion of the top surface of the second electrode branch 22B disposed on the second inner bank 42. That is, the second insulating layer 52 may be substantially entirely formed on the first insulating layer 51, and may include an opening partially exposing the first electrode 21 and the second electrode 22.
In an embodiment, the second insulating layer 52 may be formed to have a step between the first electrode 21 and the second electrode 22 such that a portion of the top surface thereof is recessed between the first electrode 21 and the second electrode 22. In some embodiments, the second insulating layer 52 may include an inorganic insulating material, and a portion of a top surface of the second insulating layer 52 disposed to cover the first electrode 21 and the second electrode 22 may be recessed due to a step of a member disposed thereunder. The light emitting element 30 disposed on the second insulating layer 52 between the first electrode 21 and the second electrode 22 may form an empty space with respect to the recessed top surface of the second insulating layer 52. The light emitting element 30 may be disposed to be partially spaced apart from the top surface of the second insulating layer 52, and a material forming a third insulating layer 53 to be described later may be filled in the space. However, the disclosure is not limited thereto. The second insulating layer 52 may form a flat top surface such that the light emitting element 30 is disposed thereon.
The second insulating layer 52 may protect the first electrode 21 and the second electrode 22 while insulating them from each other. Further, the light emitting element 30 provided on the second insulating layer 52 can be prevented from being damaged by direct contact with other members. However, the shape and structure of the second insulating layer 52 are not limited thereto.
The light emitting element 30 may be disposed on the second insulating layer 52 between the electrodes 21 and 22. For example, at least one light emitting element 30 may be disposed on the second insulating layer 52 disposed between the respective electrode branches 21B and 22B. However, the disclosure is not limited thereto, and although not shown in the drawings, at least some of the light emitting elements 30 provided in each subpixel PXn may be provided in an area other than the area between the respective electrode branches 21B and 22B. The light emitting element 30 may be disposed on each of the ends of the first and second electrode branches 21B and 22B facing each other, and may be electrically connected to each of the electrodes 21 and 22 through the contact electrode 26.
In the light emitting element 30, a plurality of layers may be provided in a horizontal direction with respect to the first insulating layer 51. The light emitting element 30 of the display device 10 according to one embodiment may have a shape extending in one direction, and may have a structure in which a plurality of semiconductor layers are sequentially arranged in one direction. As described above, in the light emitting element 30, the first semiconductor layer 31, the active layer 33, the second semiconductor layer 32, and the electrode layer 37 may be sequentially disposed along one direction, and the insulating film 38 may surround the outer surface thereof. The light emitting element 30 provided in the display device 10 may be provided such that one extending direction is parallel to the first insulating layer 51, and a plurality of semiconductor layers included in the light emitting element 30 may be sequentially provided along a direction parallel to the top surface of the first insulating layer 51. However, the disclosure is not limited thereto. In some cases, when the light emitting element 30 has a different structure, a plurality of layers may be disposed in a direction perpendicular to the first insulating layer 51.
In addition, one end of the light emitting element 30 may be in contact with the first contact electrode 26a, and the other end of the light emitting element 30 may be in contact with the second contact electrode 26 b. According to one embodiment, since the light emitting element 30 has an end surface on which the insulating film 38 is not formed on one side in one extending direction and is exposed, the light emitting element 30 can be in contact with a first contact electrode 26a and a second contact electrode 26b, which will be described later, in the exposed region. However, the disclosure is not limited thereto. In some cases, in the light emitting element 30, at least some regions of the insulating film 38 may be removed, and the insulating film 38 may be removed to partially expose both end side surfaces of the light emitting element 30.
The third insulating layer 53 may be partially disposed on the light emitting element 30 disposed between the first electrode 21 and the second electrode 22. The third insulating layer 53 may be disposed to partially surround the outer surface of the light emitting element 30. The third insulating layer 53 may be used to protect the light emitting element 30 and also fix the light emitting element 30 in the manufacturing process of the display device 10. Further, in the embodiment, a part of the material of the third insulating layer 53 may be disposed between the bottom surface of the light emitting element 30 and the second insulating layer 52. As described above, the third insulating layer 53 may be formed to fill the space formed between the second insulating layer 52 and the light emitting element 30 during the manufacturing process of the display device 10. Accordingly, the third insulating layer 53 may be formed to surround the outer surface of the light emitting element 30. However, the disclosure is not limited thereto.
In a plan view, the third insulating layer 53 may be disposed to extend in the fifth direction DR5 between the first electrode branch 21B and the second electrode branch 22B. For example, in a plan view, the third insulating layer 53 may have an island shape or a linear shape on the first insulating layer 51. According to one embodiment, the third insulating layer 53 may be disposed over the light emitting element 30.
The first contact electrode 26a and the second contact electrode 26b are provided on the electrodes 21 and 22, respectively, and on the third insulating layer 53. The first contact electrode 26a and the second contact electrode 26b may be disposed to be spaced apart from each other on the third insulating layer 53. The third insulating layer 53 may insulate the first contact electrode 26a and the second contact electrode 26b from each other so that they are not in direct contact with each other.
The first contact electrode 26a may be in contact with exposed areas of the first electrode 21 on the first inner bank 41, and the second contact electrode 26b may be in contact with exposed areas of the second electrode 22 on the second inner bank 42. The first contact electrode 26a and the second contact electrode 26b may transmit the electric signals transmitted from the respective electrodes 21 and 22 to the light emitting element 30.
The contact electrode 26 may include a conductive material. For example, they may include ITO, IZO, ITZO or aluminum (Al) or the like. However, it is not limited thereto.
A passivation layer 55 may be disposed on the contact electrode 26 and the third insulating layer 53. The passivation layer 55 may serve to protect the components disposed on the first insulating layer 51 from the external environment.
Each of the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 described above may include an inorganic insulating material or an organic insulating material. In an embodiment, the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 may include a material such as silicon oxide (SiO x ) Silicon nitride (SiN) x ) Silicon oxynitride (SiO) x N y ) Alumina (Al) 2 O 3 ) And an inorganic insulating material of aluminum nitride (AlN). In addition, the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 may include organic insulating materials such as acrylic resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene sulfide resin, benzocyclobutene, cado resin, silicone resin, silsesquioxane resin, polymethyl methacrylate, polycarbonate, and polymethyl methacrylate-polycarbonate synthetic resin. However, it is not limited thereto.
Fig. 29 to 31 are cross-sectional views partially illustrating a method of manufacturing a display device according to one embodiment.
Referring to fig. 29 to 31, the display device 10 according to one embodiment may be manufactured using the inkjet printing device 1000 described above with reference to fig. 1. The inkjet printing device 1000 may spray the ink 90 in which the light emitting elements 30 are dispersed, and the light emitting elements 30 may be disposed between the first electrode 21 and the second electrode 22 of the display device 10.
First, as shown in fig. 29, a first insulating layer 51, first and second inner banks 41 and 42 disposed on the first insulating layer 51 to be spaced apart from each other, first and second electrodes 21 and 22 disposed on the first and second inner banks 41 and 42, respectively, and a second insulating material layer 52' covering the first and second electrodes 21 and 22 are prepared. The second insulating material layer 52' may be partially patterned in a subsequent process to form the second insulating layer 52 of the display device 10. The member may be formed by patterning a metal, an inorganic material, an organic material, or the like by performing a conventional mask process.
Next, the ink 90 in which the light emitting element 30 is dispersed is sprayed on the first electrode 21 and the second electrode 22. The light emitting element 30 is a bipolar element, and the ink 90 in which the light emitting element 30 is dispersed may be sprayed using the inkjet printing apparatus 1000 and the above-described bipolar element alignment method. As shown in the drawing, in the ink 90 sprayed by the inkjet printing apparatus 1000 according to one embodiment, the light emitting elements 30 extending in one direction may be dispersed, and the light emitting elements 30 may be sprayed in a state where one extending direction is perpendicular to the top surface of the first insulating layer 51. The description thereof is the same as the above description, and thus a detailed description thereof will be omitted.
Next, as shown in fig. 30, an electric signal is applied to the first electrode 21 and the second electrode 22 to generate an electric field IEL in the ink 90 in which the light emitting element 30 is dispersed. The light emitting element 30 may be subjected to dielectrophoresis force by the electric field IEL, so that it may be placed between the first electrode 21 and the second electrode 22 while its orientation direction and position are changed.
Next, as shown in fig. 31, the solvent 91 of the ink 90 is removed. Through the above process, the light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22. Thereafter, although not shown in the drawings, the second insulating material layer 52' may be patterned to form the second insulating layer 52, and the third insulating layer 53, the first and second contact electrodes 26a and 26b, and the passivation layer 55 may be formed to manufacture the display device 10.
According to the method of manufacturing the display device 10 using the inkjet printing device 1000 according to one embodiment, the light emitting element 30 can be aligned between the first electrode 21 and the second electrode 22 with a high degree of alignment. The light emitting element 30 having an improved alignment degree may reduce poor connection or contact between the respective electrodes 21 and 22 or the contact electrodes 26a and 26b, and may improve emission reliability of each pixel PX of the display device 10.
In the final detailed description, those skilled in the art will understand that many variations and modifications may be made to the preferred embodiment without substantially departing from the principles of the invention. Accordingly, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (24)

1. An inkjet printing apparatus for ejecting ink including a bipolar element extending in one direction, the inkjet printing apparatus comprising:
an electric field generating unit including a stage and a probe unit generating an electric field on the stage; and
an inkjet head positioned above the stage and including a plurality of nozzles from which the ink is ejected,
wherein the nozzle comprises an inlet having a first diameter and an outlet connected to the inlet and having a second diameter smaller than the first diameter, and
wherein the inkjet head includes electric field generating parts provided on side surfaces of the inlet and the outlet and configured to generate an electric field such that first and second ends of the bipolar element face a specific direction.
2. The inkjet printing apparatus according to claim 1 wherein, in the nozzle, a first side surface that is one side surface of the outlet extends in a first direction, and
The second side surface, which is one side surface of the inlet, is formed to be inclined with respect to the first direction.
3. The inkjet printing apparatus of claim 2 wherein the ink is introduced into the outlet through the inlet and
the bipolar element is introduced into the outlet along the second side surface of the nozzle.
4. An inkjet printing apparatus according to claim 3 wherein the bipolar element is ejected from the outlet with its direction of extension parallel to the first direction.
5. The inkjet printing apparatus of claim 2 wherein the inkjet head further comprises a guide member positioned between the plurality of nozzles, and
the guide members include a first guide member between the outlets and a second guide member between the inlets.
6. The inkjet printing apparatus according to claim 5 wherein the electric field generating member includes a first electric field generating electrode disposed on one surface of the first guide member in contact with the first side surface and a second electric field generating electrode disposed on one surface of the second guide member in contact with the second side surface and spaced apart from the first electric field generating electrode in the first direction.
7. The inkjet printing apparatus of claim 6, wherein the first and second electric field generating electrodes generate an electric field in the first direction at the inlet and the outlet.
8. The inkjet printing apparatus of claim 5, wherein the electric field generating means comprises an electric field generating coil disposed around the nozzle.
9. The inkjet printing apparatus of claim 8, wherein the electric field generating coil generates an electric field in the first direction at the inlet and the outlet.
10. The inkjet printing apparatus of claim 2 wherein the inkjet head further comprises an inner tube connected to the inlet, and
the first diameter of the inlet decreases from the inner tube to the outlet.
11. The inkjet printing apparatus of claim 10 wherein the inkjet head further comprises a plurality of third guide members disposed between the inlet and the inner tube, and
the nozzle further comprises an inlet pipe formed by a separation space between the inner pipe and the inlet, between the third guide member.
12. The inkjet printing apparatus according to claim 11 wherein the ink is supplied from the inner tube to the inlet along the inlet tube, and
The bipolar element is introduced to the second side surface along one side surface of the inlet tube.
13. The inkjet printing apparatus according to claim 1 wherein the inkjet head is provided on a printhead unit mounted on a carriage extending in one direction, and
the print head unit moves in the one direction.
14. The inkjet printing apparatus of claim 2 wherein the ejected ink is sprayed onto the table, and
the electric field generating unit generates an electric field on the stage.
15. The inkjet printing apparatus according to claim 14 wherein the bipolar elements sprayed onto the table are aligned by the electric field generated by the electric field generating unit such that the extending direction of the bipolar elements points in a second direction different from the first direction.
16. A method for aligning bipolar elements, the method comprising the steps of:
spraying the ink comprising the bipolar element onto a target substrate by using the inkjet printing apparatus according to claim 1; and
an electric field is generated over the target substrate to place the bipolar element on the target substrate.
17. The method of claim 16, wherein the step of spraying the ink is performed in a state in which an orientation direction of a long axis of the bipolar element is perpendicular to a top surface of the target substrate.
18. The method of claim 17, wherein the step of spraying the ink comprises generating the electric field in the ink by the electric field generating means such that the long axis of the bipolar element is oriented in a direction in which the electric field is directed.
19. The method of claim 18, wherein the ink is sprayed in a state in which a first end of the bipolar element is oriented toward the top surface of the target substrate.
20. The method of claim 16, wherein the target substrate comprises a first electrode and a second electrode, and
the step of placing the bipolar element includes placing the bipolar element between the first electrode and the second electrode.
21. The method of claim 20, wherein at least one end of the bipolar element is disposed on at least one of the first electrode and the second electrode.
22. A method for manufacturing a display device, the method comprising the steps of:
Preparing a target substrate having a first electrode and a second electrode formed thereon;
spraying ink including a light emitting element oriented in one direction onto the target substrate by using the inkjet printing apparatus according to claim 1; and
the light emitting element is placed between the first electrode and the second electrode.
23. The method according to claim 22, wherein the light-emitting element has a shape extending in one direction, and
the step of spraying the ink is performed in a state in which the orientation direction of the long axis of the light emitting element is perpendicular to the top surface of the target substrate.
24. The method of claim 23, wherein the step of placing the light-emitting element further comprises generating an electric field across the first electrode and the second electrode, and
the orientation direction of the light emitting element is aligned by the electric field.
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